1,679

Keedysville, MD Homes

Section Image
    • 4657 Mount Briar Rd, Keedysville, MD 21756
      4657 Mount Briar Rd, Keedysville, MD 21756
      4657 Mount Briar Rd, Keedysville, MD 21756
      /16

      Est $269,180 Not Listed For Sale

      4657 Mount Briar Rd, Keedysville, MD 21756

      • 3 Beds
      • 1 Bath
      • 1,788 Sq Ft
      • Built 1869
      4657 Mount Briar Rd, Keedysville, MD 21756

      Last Sold Summary

      • 63% Above List Price
      • $92/SF
      • 4 Days On Market

      Last Sold Price $164,900

      Last Listing Agent Roger Fairbourn Roger Fairbourn Real Estate

    • 19546 Elk Ridge Dr, Keedysville, MD 21756
      19546 Elk Ridge Dr, Keedysville, MD 21756
      19546 Elk Ridge Dr, Keedysville, MD 21756
      /40

      Est $442,316 Not Listed For Sale

      19546 Elk Ridge Dr, Keedysville, MD 21756

      • 4 Beds
      • 3 Baths
      • 2,432 Sq Ft
      • Built 2003
      19546 Elk Ridge Dr, Keedysville, MD 21756

      Last Sold Summary

      • 11% Above List Price
      • $164/SF
      • 125 Days On Market

      Last Sold Price $399,000

      Last Listing Agent Kellie Plucinski Long & Foster

    • 2630 Hawks Hill Ln, Keedysville, MD 21756
      2630 Hawks Hill Ln, Keedysville, MD 21756
      2630 Hawks Hill Ln, Keedysville, MD 21756
      /23

      Est $291,064 Not Listed For Sale

      2630 Hawks Hill Ln, Keedysville, MD 21756

      • 1 Bed
      • 1 Bath
      • 1,800 Sq Ft
      • Built 1987
      2630 Hawks Hill Ln, Keedysville, MD 21756

      Last Sold Summary

      • 101% Above List Price
      • $81/SF
      • 94 Days On Market

      Last Sold Price $145,000

      Last Listing Agent Becky Wibberley Coldwell Banker (NRT-Southeast-MidAtlantic)

    • 4912 Porterstown Rd, Keedysville, MD 21756
      4912 Porterstown Rd, Keedysville, MD 21756
      4912 Porterstown Rd, Keedysville, MD 21756
      /12

      Est $312,262 Not Listed For Sale

      4912 Porterstown Rd, Keedysville, MD 21756

      • 3 Beds
      • 2 Baths
      • 1,471 Sq Ft
      • Built 1966
      4912 Porterstown Rd, Keedysville, MD 21756

      Last Sold Summary

      • 123% Above List Price
      • $95/SF
      • 11 Days On Market

      Last Sold Price $140,000

      Last Listing Agent Charles Jenkins Charles Jenkins Signpost Realty

    • 18 Mt Vernon Dr, Keedysville, MD 21756
      18 Mt Vernon Dr, Keedysville, MD 21756
      18 Mt Vernon Dr, Keedysville, MD 21756
      /31

      Est $372,282 Not Listed For Sale

      18 Mt Vernon Dr, Keedysville, MD 21756

      • 3 Beds
      • 2 Baths
      • 1,374 Sq Ft
      • Built 2020
      18 Mt Vernon Dr, Keedysville, MD 21756

      Last Sold Summary

      • 22% Above List Price
      • $222/SF
      • 5 Days On Market

      Last Sold Price $305,000

      Last Listing Agent Matt Patterson Long & Foster Real Estate, Inc.

    • 3 & 5 N Main St, Keedysville, MD 21756
      3 & 5 N Main St, Keedysville, MD 21756
      3 & 5 N Main St, Keedysville, MD 21756
      /6

      Not Listed For Sale

      3 & 5 N Main St, Keedysville, MD 21756

      • Studio
      • 5,013 Sq Ft
      • Built 1862
      3 & 5 N Main St, Keedysville, MD 21756

      Last Sold Summary

      • $106/SF
      • 4 Days On Market

      Last Sold Price $530,000

      Last Listing Agent Darrell Ferguson 3% Realty Elite, Simply Full Service Realty

    • 12.61 Acres Red Hill Rd, Keedysville, MD 21756
      12.61 Acres Red Hill Rd, Keedysville, MD 21756
      12.61 Acres Red Hill Rd, Keedysville, MD 21756
      /27

      Not Listed For Sale

      12.61 Acres Red Hill Rd, Keedysville, MD 21756

      12.61 Acres Red Hill Rd, Keedysville, MD 21756

      Last Sold Summary

      • 315 Days On Market

      Last Sold Price $108,000

      Last Listing Agent Shelby Diehl EXP Realty, LLC

    • 157 Stonecrest Cir, Keedysville, MD 21756
      157 Stonecrest Cir, Keedysville, MD 21756
      157 Stonecrest Cir, Keedysville, MD 21756
      /38

      Est $489,491 Not Listed For Sale

      157 Stonecrest Cir, Keedysville, MD 21756

      • 4 Beds
      • 2.5 Baths
      • 2,544 Sq Ft
      • Built 2017
      157 Stonecrest Cir, Keedysville, MD 21756

      Last Sold Summary

      • 19% Above List Price
      • $162/SF
      • 14 Days On Market

      Last Sold Price $411,400

      Last Listing Agent Laura Malec EXP Realty, LLC

    • 154 Stonecrest Cir, Keedysville, MD 21756
      154 Stonecrest Cir, Keedysville, MD 21756
      154 Stonecrest Cir, Keedysville, MD 21756
      /58

      Est $650,903 Not Listed For Sale

      154 Stonecrest Cir, Keedysville, MD 21756

      • 4 Beds
      • 4.5 Baths
      • 5,694 Sq Ft
      • Built 2018
      154 Stonecrest Cir, Keedysville, MD 21756

      Last Sold Summary

      • 18% Above List Price
      • $97/SF
      • 5 Days On Market

      Last Sold Price $551,000

      Last Listing Agent Brian King Samson Properties

    • 114 Stonecrest Cir, Keedysville, MD 21756
      114 Stonecrest Cir, Keedysville, MD 21756
      114 Stonecrest Cir, Keedysville, MD 21756
      /61

      Est $570,412 Not Listed For Sale

      114 Stonecrest Cir, Keedysville, MD 21756

      • 4 Beds
      • 2.5 Baths
      • 5,400 Sq Ft
      • Built 2018
      114 Stonecrest Cir, Keedysville, MD 21756

      Last Sold Summary

      • 7% Above List Price
      • $99/SF
      • 29 Days On Market

      Last Sold Price $532,000

      Last Listing Agent Jay Day LPT Realty, LLC

    • 4751 Horizon Ln, Keedysville, MD 21756
      4751 Horizon Ln, Keedysville, MD 21756
      4751 Horizon Ln, Keedysville, MD 21756
      /41

      Est $1,093,781 Not Listed For Sale

      4751 Horizon Ln, Keedysville, MD 21756

      • 4 Beds
      • 3 Baths
      • 2,502 Sq Ft
      • Built 1998
      4751 Horizon Ln, Keedysville, MD 21756

      Last Sold Summary

      • 5% Above List Price
      • $416/SF
      • 78 Days On Market

      Last Sold Price $1,040,000

      Last Listing Agent Corey Burr TTR Sotheby's International Realty

    • 4705 Horizon Ln, Keedysville, MD 21756
      4705 Horizon Ln, Keedysville, MD 21756
      4705 Horizon Ln, Keedysville, MD 21756
      /70

      Est $681,589 Not Listed For Sale

      4705 Horizon Ln, Keedysville, MD 21756

      • 3 Beds
      • 2 Baths
      • 3,922 Sq Ft
      • Built 1999
      4705 Horizon Ln, Keedysville, MD 21756

      Last Sold Summary

      • 17% Above List Price
      • $149/SF
      • 4 Days On Market

      Last Sold Price $585,000

      Last Listing Agent Jay Day LPT Realty, LLC

    • 6332 Coffman Farms Rd, Keedysville, MD 21756
      6332 Coffman Farms Rd, Keedysville, MD 21756
      6332 Coffman Farms Rd, Keedysville, MD 21756
      /65

      Est $550,645 Not Listed For Sale

      6332 Coffman Farms Rd, Keedysville, MD 21756

      • 4 Beds
      • 3 Baths
      • 2,208 Sq Ft
      • Built 1988
      6332 Coffman Farms Rd, Keedysville, MD 21756

      Last Sold Summary

      • 22% Above List Price
      • $204/SF
      • 7 Days On Market

      Last Sold Price $450,000

      Last Listing Agent Bill Kenny Keller Williams Realty Centre

    • 0 Red Hill Rd Unit MDWA167456, Keedysville, MD 21756
      0 Red Hill Rd Unit MDWA167456, Keedysville, MD 21756
      0 Red Hill Rd Unit MDWA167456, Keedysville, MD 21756
      /15

      Not Listed For Sale

      0 Red Hill Rd Unit MDWA167456, Keedysville, MD 21756

      0 Red Hill Rd Unit MDWA167456, Keedysville, MD 21756

      Last Sold Summary

      • 162 Days On Market

      Last Sold Price $80,000

      Last Listing Agent Shelby Diehl EXP Realty, LLC

    • LOT B Trego Rd E, Keedysville, MD 21756
      LOT B Trego Rd E, Keedysville, MD 21756
      LOT B Trego Rd E, Keedysville, MD 21756
      /7

      Not Listed For Sale

      LOT B Trego Rd E, Keedysville, MD 21756

      LOT B Trego Rd E, Keedysville, MD 21756

      Last Sold Summary

      • 1,084 Days On Market

      Last Sold Price $108,000

      Last Listing Agent Tracy Mentzer Coldwell Banker (NRT-Southeast-MidAtlantic)

    • 0 Hardwood Ln Unit 1000150043, Keedysville, MD 21756
      0 Hardwood Ln Unit 1000150043, Keedysville, MD 21756
      0 Hardwood Ln Unit 1000150043, Keedysville, MD 21756
      /3

      Not Listed For Sale

      0 Hardwood Ln Unit 1000150043, Keedysville, MD 21756

      0 Hardwood Ln Unit 1000150043, Keedysville, MD 21756

      Last Sold Summary

      • 812 Days On Market

      Last Sold Price $130,000

      Last Listing Agent Shirley Happ Happ Realty & Associates, Inc.

    • 0 Trego Mountain Rd Unit 1004073061, Keedysville, MD 21756
      0 Trego Mountain Rd Unit 1004073061, Keedysville, MD 21756
      0 Trego Mountain Rd Unit 1004073061, Keedysville, MD 21756
      /13

      Not Listed For Sale

      0 Trego Mountain Rd Unit 1004073061, Keedysville, MD 21756

      0 Trego Mountain Rd Unit 1004073061, Keedysville, MD 21756

      Last Sold Summary

      • 123 Days On Market

      Last Sold Price $109,000

      Last Listing Agent Kimberley Gundacker Berkshire Hathaway HomeServices Homesale Realty

    • 146 Stonecrest Cir, Keedysville, MD 21756
      146 Stonecrest Cir, Keedysville, MD 21756
      146 Stonecrest Cir, Keedysville, MD 21756
      /27

      Est $488,934 Not Listed For Sale

      146 Stonecrest Cir, Keedysville, MD 21756

      • 4 Beds
      • 2.5 Baths
      • 2,040 Sq Ft
      • Built 2017
      146 Stonecrest Cir, Keedysville, MD 21756

      Last Sold Summary

      • 63% Above List Price
      • $147/SF
      • 2 Days On Market

      Last Sold Price $299,900

      Last Listing Agent John Potter RE/MAX

    • 18952 Planters Ln, Keedysville, MD 21756
      18952 Planters Ln, Keedysville, MD 21756
      18952 Planters Ln, Keedysville, MD 21756
      /30

      Not Listed For Sale

      18952 Planters Ln, Keedysville, MD 21756

      • 4 Beds
      • 2 Baths
      • 2,128 Sq Ft
      • Built 2007
      18952 Planters Ln, Keedysville, MD 21756

      Last Sold Summary

      • $117/SF
      • 78 Days On Market

      Last Sold Price $250,000

      Last Listing Agent Michael Fitzgerald Exit Success Realty

    • 110 Stonecrest Cir, Keedysville, MD 21756
      110 Stonecrest Cir, Keedysville, MD 21756
      110 Stonecrest Cir, Keedysville, MD 21756
      /43

      Est $491,399 Not Listed For Sale

      110 Stonecrest Cir, Keedysville, MD 21756

      • 4 Beds
      • 2.5 Baths
      • 2,288 Sq Ft
      • Built 2017
      110 Stonecrest Cir, Keedysville, MD 21756

      Last Sold Summary

      • 60% Above List Price
      • $134/SF
      • 7 Days On Market

      Last Sold Price $307,500

      Last Listing Agent Chris Dickerson The Glocker Group Realty Results

    • 5 N Main St Unit 3C, Keedysville, MD 21756
      5 N Main St Unit 3C, Keedysville, MD 21756
      /2

      Not Listed For Sale

      5 N Main St Unit 3C, Keedysville, MD 21756

      • 1 Bed
      • 1 Bath
      • 4,290 Sq Ft
      • Built 1871
      5 N Main St Unit 3C, Keedysville, MD 21756

      Last Sold Summary

      Last Listing Agent Rose Creasey Allied Enterprises, LLC

    • 5 N Main St Unit 3B, Keedysville, MD 21756
      5 N Main St Unit 3B, Keedysville, MD 21756
      /2

      Not Listed For Sale

      5 N Main St Unit 3B, Keedysville, MD 21756

      • 1 Bed
      • 1 Bath
      • 500 Sq Ft
      • Built 1810
      5 N Main St Unit 3B, Keedysville, MD 21756

      Last Sold Summary

      Last Listing Agent Anna Williams Taylor Properties

    • 19232 Porterstown Rd, Keedysville, MD 21756
      19232 Porterstown Rd, Keedysville, MD 21756
      19232 Porterstown Rd, Keedysville, MD 21756
      /10

      Est $372,456 Not Listed For Sale

      19232 Porterstown Rd, Keedysville, MD 21756

      • Built 2021
      19232 Porterstown Rd, Keedysville, MD 21756

      Last Sold Summary

      • 473% Above List Price
      • $68/SF
      • 70 Days On Market

      Last Sold Price $65,000

      Last Listing Agent Molly King Real Estate Innovations

    • 6714 Hardwood Ln, Keedysville, MD 21756
      6714 Hardwood Ln, Keedysville, MD 21756
      6714 Hardwood Ln, Keedysville, MD 21756
      /48

      Est $670,596 Not Listed For Sale

      6714 Hardwood Ln, Keedysville, MD 21756

      • 3 Beds
      • 3 Baths
      • 2,341 Sq Ft
      • Built 2003
      6714 Hardwood Ln, Keedysville, MD 21756

      Last Sold Summary

      • 41% Above List Price
      • $203/SF
      • 4 Days On Market

      Last Sold Price $475,000

      Last Listing Agent Matt Patterson Long & Foster Real Estate, Inc.

    • 4423 Chestnut Grove Rd, Keedysville, MD 21756
      4423 Chestnut Grove Rd, Keedysville, MD 21756
      4423 Chestnut Grove Rd, Keedysville, MD 21756
      /11

      Not Listed For Sale

      4423 Chestnut Grove Rd, Keedysville, MD 21756

      4423 Chestnut Grove Rd, Keedysville, MD 21756

      Last Sold Summary

      • 448 Days On Market

      Last Sold Price $202,000

      Last Listing Agent Frank Getz Real Estate Innovations

    • 25 Antietam Dr, Keedysville, MD 21756
      25 Antietam Dr, Keedysville, MD 21756
      25 Antietam Dr, Keedysville, MD 21756
      /7

      Est $182,562 Not Listed For Sale

      25 Antietam Dr, Keedysville, MD 21756

      • 2 Beds
      • 1 Bath
      • 1,056 Sq Ft
      • Built 1900
      25 Antietam Dr, Keedysville, MD 21756

      Last Sold Summary

      • 288% Above List Price
      • $45/SF
      • 49 Days On Market

      Last Sold Price $47,000

      Last Listing Agent Eddie Jefferson The Glocker Group Realty Results

    • 28 Antietam Dr, Keedysville, MD 21756
      28 Antietam Dr, Keedysville, MD 21756
      28 Antietam Dr, Keedysville, MD 21756
      /15

      Est $255,438 Not Listed For Sale

      28 Antietam Dr, Keedysville, MD 21756

      • 3 Beds
      • 1 Bath
      • 1,520 Sq Ft
      • Built 1910
      28 Antietam Dr, Keedysville, MD 21756

      Last Sold Summary

      • 232% Above List Price
      • $51/SF
      • 258 Days On Market

      Last Sold Price $77,000

      Last Listing Agent Eddie Jefferson The Glocker Group Realty Results

    • 18546 Keedysville Rd, Keedysville, MD 21756
      18546 Keedysville Rd, Keedysville, MD 21756
      18546 Keedysville Rd, Keedysville, MD 21756
      /4

      Est $467,606 Not Listed For Sale

      18546 Keedysville Rd, Keedysville, MD 21756

      • Built 2016
      18546 Keedysville Rd, Keedysville, MD 21756

      Last Sold Summary

      • 392% Above List Price
      • $58/SF
      • 161 Days On Market

      Last Sold Price $95,000

      Last Listing Agent Jason Hose Mackintosh, Inc.

    • 22 Bell Ln, Keedysville, MD 21756
      22 Bell Ln, Keedysville, MD 21756
      22 Bell Ln, Keedysville, MD 21756
      /24

      Est $282,075 Not Listed For Sale

      22 Bell Ln, Keedysville, MD 21756

      • 2 Beds
      • 1.5 Baths
      • 1,104 Sq Ft
      • Built 1856
      22 Bell Ln, Keedysville, MD 21756

      Last Sold Summary

      • 76% Above List Price
      • $145/SF
      • 128 Days On Market

      Last Sold Price $160,000

      Last Listing Agent Steve Powell Samson Properties

    • 6 N Main St Unit 1, Keedysville, MD 21756
      6 N Main St Unit 1, Keedysville, MD 21756
      /2

      Est $334,367 Not Listed For Sale

      6 N Main St Unit 1, Keedysville, MD 21756

      • 3 Beds
      • 1 Bath
      • 3,651 Sq Ft
      • Built 1880
      6 N Main St Unit 1, Keedysville, MD 21756

      Last Sold Summary

      Last Listing Agent Josephine Cicolini BHHS PenFed (actual)

    • 5304 Red Hill Rd, Keedysville, MD 21756
      5304 Red Hill Rd, Keedysville, MD 21756
      5304 Red Hill Rd, Keedysville, MD 21756
      /5

      Not Listed For Sale

      5304 Red Hill Rd, Keedysville, MD 21756

      5304 Red Hill Rd, Keedysville, MD 21756

      Last Sold Summary

      • 215 Days On Market

      Last Sold Price $66,000

      Last Listing Agent Jim Bass Real Estate Teams, LLC

    • 3 N Main St Unit 3A, Keedysville, MD 21756
      3 N Main St Unit 3A, Keedysville, MD 21756
      /2

      Not Listed For Sale

      3 N Main St Unit 3A, Keedysville, MD 21756

      • 3 Beds
      • 1 Bath
      • 5,013 Sq Ft
      • Built 1862
      3 N Main St Unit 3A, Keedysville, MD 21756

      Last Sold Summary

      Last Listing Agent Rose Creasey Allied Enterprises, LLC

    • 19134 Shepherdstown Pike, Keedysville, MD 21756
      19134 Shepherdstown Pike, Keedysville, MD 21756
      19134 Shepherdstown Pike, Keedysville, MD 21756
      /29

      Not Listed For Sale

      19134 Shepherdstown Pike, Keedysville, MD 21756

      • 2 Beds
      • 1 Bath
      • Built 1970
      19134 Shepherdstown Pike, Keedysville, MD 21756

      Last Sold Summary

      • 260 Days On Market

      Last Sold Price $123,000

      Last Listing Agent Syd Machat Sydney Machat, Broker

    • 10 Bell Ln, Keedysville, MD 21756
      10 Bell Ln, Keedysville, MD 21756
      10 Bell Ln, Keedysville, MD 21756
      /42

      Est $278,347 Not Listed For Sale

      10 Bell Ln, Keedysville, MD 21756

      • 3 Beds
      • 2 Baths
      • 975 Sq Ft
      • Built 1900
      10 Bell Ln, Keedysville, MD 21756

      Last Sold Summary

      • 45% Above List Price
      • $197/SF
      • 8 Days On Market

      Last Sold Price $192,000

      Last Listing Agent Karen Demeza J&B Real Estate

    • 4637 Pennyhill Ln, Keedysville, MD 21756
      4637 Pennyhill Ln, Keedysville, MD 21756
      4637 Pennyhill Ln, Keedysville, MD 21756
      /3

      Est $246,423 Not Listed For Sale

      4637 Pennyhill Ln, Keedysville, MD 21756

      4637 Pennyhill Ln, Keedysville, MD 21756

      Last Sold Summary

      • 97% Above List Price
      • 2 Days On Market

      Last Sold Price $125,000

      Last Listing Agent Roger Fairbourn Roger Fairbourn Real Estate

    • 19750 Dogstreet Rd, Keedysville, MD 21756
      19750 Dogstreet Rd, Keedysville, MD 21756
      19750 Dogstreet Rd, Keedysville, MD 21756
      /29

      Est $808,227 Not Listed For Sale

      19750 Dogstreet Rd, Keedysville, MD 21756

      • 5 Beds
      • 4 Baths
      • 4,044 Sq Ft
      • Built 2009
      19750 Dogstreet Rd, Keedysville, MD 21756

      Last Sold Summary

      • 86% Above List Price
      • $108/SF
      • 174 Days On Market

      Last Sold Price $435,000

      Last Listing Agent Brian Greenberg Charis Realty Group

    • 48 Sumter Dr, Keedysville, MD 21756
      48 Sumter Dr, Keedysville, MD 21756
      48 Sumter Dr, Keedysville, MD 21756
      /30

      Est $462,161 Not Listed For Sale

      48 Sumter Dr, Keedysville, MD 21756

      • 4 Beds
      • 2.5 Baths
      • 2,058 Sq Ft
      • Built 2009
      48 Sumter Dr, Keedysville, MD 21756

      Last Sold Summary

      • 68% Above List Price
      • $134/SF
      • 111 Days On Market

      Last Sold Price $275,000

      Last Listing Agent Jay Day LPT Realty, LLC

    • 17 Farragut Dr, Keedysville, MD 21756
      17 Farragut Dr, Keedysville, MD 21756
      17 Farragut Dr, Keedysville, MD 21756
      /24

      Est $521,788 Not Listed For Sale

      17 Farragut Dr, Keedysville, MD 21756

      • 4 Beds
      • 2.5 Baths
      • 2,743 Sq Ft
      • Built 2009
      17 Farragut Dr, Keedysville, MD 21756

      Last Sold Summary

      • 86% Above List Price
      • $102/SF
      • 67 Days On Market

      Last Sold Price $280,000

      Last Listing Agent Philip Piantone Long & Foster

    • 4208 Trego Rd, Keedysville, MD 21756
      4208 Trego Rd, Keedysville, MD 21756
      4208 Trego Rd, Keedysville, MD 21756
      /30

      Est $457,226 Not Listed For Sale

      4208 Trego Rd, Keedysville, MD 21756

      • 5 Beds
      • 3 Baths
      • 2,176 Sq Ft
      • Built 1957
      4208 Trego Rd, Keedysville, MD 21756

      Last Sold Summary

      • 43% Above List Price
      • $147/SF
      • 77 Days On Market

      Last Sold Price $320,000

      Last Listing Agent Roberta McNamara RE/MAX

    • 18638 Mansfield Rd, Keedysville, MD 21756
      18638 Mansfield Rd, Keedysville, MD 21756
      18638 Mansfield Rd, Keedysville, MD 21756
      /14

      Est $214,033 Not Listed For Sale

      18638 Mansfield Rd, Keedysville, MD 21756

      • Built 1939
      18638 Mansfield Rd, Keedysville, MD 21756

      Last Sold Summary

      • 168% Above List Price
      • $100/SF
      • 264 Days On Market

      Last Sold Price $80,000

      Last Listing Agent Shirley Bayer RE/MAX

Showing Results 201 - 240, Page 6 of 18

Maryland Washington County Keedysville

Real Estate & Homes

How to Buy a Home How to Finance a Home How to Sell a Home

Disclaimer: Certain information contained herein is derived from information provided by parties other than Homes.com. All information provided is deemed reliable, but is not guaranteed to be accurate and should be independently verified.

Homes.com Licensing Information

§ 442-H New York Standard Operating Procedures

New York Fair Housing Notice

TREC: Information about brokerage services, Consumer protection notice

California DRE #01937601

Contact Homes.com Brokerage

Copyright © 2026 CoStar Group