A 90-foot-tall psychedelic "tree" on the side of the highway has baffled passersby for decades.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

Come for the speed, leave in love with the desert.

This iconic science fiction house still looks like something from the future.

This tea house was a hand-built gift from Boulder's sister city in Tajikstan.

Paranormal experiences in this hotel's room 217 led Stephen King to write "The Shining."

Seller of surplus nuclear research materials.

Once a dining hall for boarding school students, this lodge was a popular haunt for nuclear physicists working on the Manhattan Project.

This bird-shaped rock formation defies gravity, time, and classification.

The most powerful laboratory radiation source in the world pulses with 1,000 times the electricity of a lightning bolt.

The home of a formerly enslaved man who went on to become a prospector, entrepreneur, and activist for Black rights.

The final resting spot of the Colorado Transportation Department's beloved unofficial mascot.

While comics are the main attraction at this megastore, the second floor plays host to an exhibit fit for a museum.

The spot in the Mile-High City that's exactly 5,280 feet above sea level (at least for now).

While most of the games in this arcade take quarters, that would have been a small fortune when they were made.

The scene of one of the darkest moments in American labor history has been left essentially untouched since the tragedy.

Hidden beneath a bridge, this waterfall is known for the large amounts of graffiti painted on its base.

This geothermal hot spring hides beneath a slowly growing mineral dome.

Curios, scientific antiques, oddities for sale.

A focal point of in Denver’s skyline for over a century, inspired by a Venetian basilica.

This sidewalk tribute honors Colorado's great culinary creation.

This Chinese-style quartz sundial was saved in its final hour.

A collection of over 15,000 zines works to preserve DIY publishing culture.

Once a mortuary that held the remains of Buffalo Bill, this Denver hotspot is now a death-fixated restaurant.