Business Insider recently published a report in which the company made an attempt to pick the ‘coolest building’ in each American state. As the publication noted, “defining what [was considered] to be the ‘coolest’ [was] hard” given how diverse America is, and while the focus was centered on architecture, the final breakdown highlights structures from a wide variety of cultures that have been present throughout American history.

Some buildings picked as the ‘coolest’ in their states were modern constructions, while others were famous chapels or historic political centers. When it came to Colorado, Business Insider had plenty of spots to choose from – the Air Force Academy Chapel, The Broadmoor, and the Stanley Hotel all come to mind as one-of-a-kind buildings that are indeed quite cool. The Business Insider pick, however, outdates those buildings by hundreds of years, with roots that go back to pre-historic times in North America.

For the ‘coolest building’ in Colorado, Business Insider selected Cliff Palace of Mesa Verde National Park. Said to be occupied by Ancestral Puebloans around 1200 AD, Cliff Palace is a structure that’s one-of-a-kind and massive in scale. It once housed around 150 cliffside rooms and 23 kivas, home to about 100 inhabitants. Of the 600-plus cliff dwellings found within the boundaries of the national park, it’s the largest, with most having between one to five rooms – not more than 100.

It’s a little unclear why its residents moved out, but from the late-13th century until the 1880s, the structure is believed to have been unoccupied. Once it was rediscovered in the 1880s, however, this led to rapid decay, as masses of visitors started to roll in while others sought to remove artifacts for personal gain.

Today, Cliff Palace is protected, but it’s still open seasonally to visitors of Mesa Verde National Park via ranger-guided tours. Undoubtedly, Cliff Palace is one of the ‘coolest’ buildings on the Business Insider list.

Find the full Business Insider list here or read Seth Boster’s account from his recent trip to the park here. Or, if you’re wanting to plan a visit, here’s the official page for Mesa Verde National Park.