Populus Hotel stands out even among Denver’s prettiest, strangest and most historic buildings.

The newly built structure catches the eye with an exterior designed to mimic an Aspen tree, with 65 different window shapes and a triangular footprint rooted in one of Denver’s busiest intersections, on the corner of West Colfax Avenue and 14th Street.

It’s the nation’s first carbon-positive hotel, developer Urban Villages has said, and the perfect place to celebrate Doors Open Denver 2024. The Sept. 26-Sunday, Sept. 29, event invites the public into local architectural wonders and offers expert commentary on their creation and history.

Attendees can also be the first to attend an event at Populus before it opens to the public on Oct. 18.

“The building is newsworthy across the country because of its sustainability approach and materials, and (for being) carbon positive,” said Meg Touborg, president and CEO of the Denver Architecture Foundation, which produces Doors Open Denver. “That level of innovation and engineering is absolutely remarkable and certainly we wanted to bring fans of Denver’s built environment inside such a novel building.”

The Doors Open Denver gala at Populus takes place from 6 to 8 p.m. on Sept. 28, and costs $150 per ticket. But you don’t have to spend that much to take part. Doors Open Denver features more than two dozen other buildings in Denver, ranging from the Globeville neighborhood in the north to Baker neighborhood in the south, that people can explore and learn about in-person, with a guide, or on a virtual audio tour.

Open sites, where people can tour at leisure, include Five Points’ Blair Caldwell African American Research Library, the Capitol Hill Mansion, and downtown’s Byron R. White U.S. Courthouse. Guided tours take place at the rest of the sites, with a map at denverarchitecture.org.