Nestled at the base of the Flatirons of Boulder, Colorado, the house known as the “Glass Tent” wasn’t just built in nature — it was built around it, with a massive boulder serving as the centerpiece of its design.
"The boulder is very Boulder,” Joel Ripmaster, listing agent with Slifer Smith & Frampton in the city, told Homes.com about the house, which has a $10 million asking price and wall after wall of glass.
Located at 333 Bellevue Drive, the 8,427-square-foot house, with five bedrooms and six and a half bathrooms, sits on a 1.24-acre lot and was built into the side of a hill.
“You’re right next to nature, in a beautiful home, surrounded by a stunning landscape,” said Matt McMullen, architect and builder of the home with Create Architecture.
McMullen recalls a time when the owners were enjoying a sunny Sunday when they spotted a bear underneath them, under the glass staircase that overlooks their koi pond.
“Sure enough, a bear was down there, reaching into the pond where they kept koi fish," McMullen said. "It was trying to catch one hiding under a rock.”
Another time, McMullen said, the owners told him about a mountain lion that casually walked up the driveway and, without a running start, leapt 15 feet onto a metal-topped wall, then strolled across it.
That’s what made the “Glass Tent” a home.
“Moments like that make you feel like you’ve done something right — creating a space where wildlife feels welcome, and you get to witness it up close,” McMullen said.
Architect inspired to capture ‘the momentum of the Earth’
McMullen said he knew the site of the property was special when he first visited it.
The home is three-tenths of a mile from Chautauqua Auditorium, a historic performance venue. What stood out to McMullen was the unique “edge condition” of the location, where the Great Plains stretch to meet the rising terrain of the Rocky Mountains. This convergence of two geological planes creates a palpable tension in the landscape, something McMullen wanted to reflect in the design of the house.
McMullen recalled being in the original house on the property when a thunderstorm blew in, buffeting the house with winds that slammed all of the doors shut.
“I thought, ‘You need to be able to really feel the momentum of the Earth. The slope of the mountains coming through the house, but you also need to feel the fact of the weather,” he said.
So, he was inspired to design the house as if it were a “glass tent.” This concept allowed anyone in the house to see the various elements of Boulder, including the Flatirons, the University of Colorado Boulder campus and more.
Design utilizes the ‘Mommy rock’ and its ‘baby’
One large boulder, already on site, became a central feature of the house.
McMullen said he and his team built the house around the boulder, which sits behind the house by the back patio.
To maintain visual continuity, McMullen said he and his team searched the Denver metropolitan area for a rock that matched the color and lichen pattern of the Flatirons and the existing boulder.
“The Mommy rock is the one by the pond, and then we had to go find a baby rock to adopt,” he said.
They found the perfect match, purchased it and used a crane to get it in place before the roof was completed. It is situated between the dining room and the kitchen.
The house’s steel frame supports the big boulder, which was drilled to allow water to flow down its surface into a visible reservoir. “It brings the sound of water into the house, and it also provides humidification for that level,” McMullen said.
Home’s interior matches its surroundings
The design was inspired by the open spaces of Boulder County, according to McMullen.
“There’s the White Rocks Open Space, and they have wetlands out there and quail that will build their nests in the reeds,” McMullen said.
The home’s design maximizes natural light. Only the main level and the primary suite — referred to as the “quail’s nest” — sit above ground, while the remaining levels, including offices, a home theater and a library, are built below grade. To bring light into these subterranean spaces, McMullen installed a glass floor along a west-facing glass wall.
Obscured glass ensures privacy between floors, McMullen said. There is Jerusalem stone on the lower-level walls, which captures the hues of the western light, making the wall golden.
It took seven years to complete
From conception to completion, the process to create the home took about seven years, with actual construction beginning in 2004 and ending in 2008, according to McMullen.
“We had to go through a bunch of processes in the city of Boulder,” McMullen said.
The property was divided into two lots: one for the main residence and the other for a 1,500-square-foot guest house, which had historically served as housing for caretakers. McMullen said he also had to revise the easement and navigate Boulder’s solar shadow ordinance.
Under the ordinance’s standard interpretation, the site’s elevation would have prevented any new construction due to the shadows it would cast on neighboring properties. To address this, McMullen proposed modeling the shadow of the original house, which predated the ordinance, and ensuring the new structure didn’t exceed that footprint. The city approved this.
“I made all those areas with low roof heights happen within closets or over the tub or in the shower — places that wouldn’t affect the overall vaulted space within the great areas, like the living room, the dining room, the kitchen, things like that,” McMullen said.
They are trying to find the right stewards
In the same year that it was completed, the home was sold to the current owners, McMullen said.
“We were trying to find the right folks who would really appreciate that home and be stewards for it,” he said. “The current owners are definitely those people.”
Since living in the home, McMullen said, the current owners have experienced the joy of being submerged in nature from the comfort of their own home.
Now the couple is retiring and moving on.
“They’re looking for the next folks who want to be the stewards for that home,” McMullen said.
Ripmaster said the house has received mixed responses from prospective buyers. “It’s very customized. It doesn’t fit everybody, even though it’s got everything that anybody would want in a house,” he said. “After you get over the wow factor, once you get into the house, you have to look to see how you would live in it.”
McMullen is no stranger to creating homes for the wealthy, from the Heinz Ketchup family to the producers of "Star Trek", but the “Glass Tent” was his most involved project.
“This definitely was the house that took the most time and had the most thought and the most detailed construction and design of my projects,” he said.
For McMullen, the best aspect of taking part in the creation of the home has been learning about the experiences his clients have had.
“They felt privileged to have lived in that home, which tells me, as a designer and builder, that we did something successful there, that we really captured what was special,” McMullen said.