The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.

A stark reminder of the huge nuclear weapons plant that once stood on the site and its effect on the surrounding area.

The library's graceful rotunda is like a bibliophile's temple.

A working steam clock, one of only a few in the world, located in Vancouver's Victorian Gastown.

A subterranean house of worship carved right out of the bedrock.

Over 300 taxidermied animals in a Californian restaurant make for a taxidermist's dream and an animal lover's nightmare.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

A winding path built in secret on the edge of the continent.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

San Francisco's newly reopened hands-on science museum.

Only hotel where you can legally launder money.

A nondescript building that's been functioning as a speakeasy for nearly a century and a half.

One of the last free public hot springs is decorated with hippie art.

Dyed by iron oxide over centuries, these sandstone rocks rise thousands of feet into the sky.

The drama of nature in full effect in this Nevada State Park.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

Hear the quietest sound from across the dome.

3,000 market stands in five former Zeppelin hangars.

A former imperial sea-fortress and Soviet prison.

The Guardian of Tallinn.

This stoic bronze soldier stands as a symbol of Russian sacrifice or Soviet oppression, or maybe both.

It houses the remains of a 17th-century version of the Titanic.