The floor of this spectacular Baroque sanctuary is covered in memento mori.

The only remaining Cold War–era Minuteman II missile control center in Missouri.

A bronze bust commemorates the heroism of the secret agents who led covert operations against the Nazis.

The last occupied troglodyte dwellings in England weren't abandoned until the 1960s.

A little-known ruin with a convoluted history and a fascinating latrine drainage system.

This museum is a portal to 20th-century Denmark.

A 12th-century church with a medieval fresco and an intriguing “Greek runestone.”

This unique temple complex remains off the typical tourist trail.

This whimsical garbage disposal facility receives around 12,000 accidental tourists each year.

The official meeting point for the oddly named governing assembly of ancient Sweden.

This remote sandstone cliff has one of the richest collections of Livonian petroglyph marks.

Originally a brothel during the Klondike Gold Rush, this bar once used dolls to denote when ladies were working.

This cave system allegedly holds the "metallic library" of a lost ancient civilization.

An engineering error ensured this cavernous 350-foot-long subterranean thoroughfare was never used as intended.

On this stunning Scottish island, you can walk in the footsteps of dinosaurs.

Live data is transmitted from the Atlantic coast to instantly recreate the ocean waves in this fountain at the NOAA headquarters.

This exceptionally well-preserved ancient marvel also houses a small museum dedicated to Jordanian folk tradition.

A nearly 25-foot concrete sculpture of Sylvette, Picasso's muse.

This dizzying span over the ancient Algerian city was once the highest suspension bridge in the world.

Outstanding, eerie frescoes and decorations fill this 19th-century monastery.

The world’s tallest outdoor lift stretches along the stone pillars that inspired the floating mountains in the movie “Avatar.”

The fire inside this temple has burned for more than 1,500 years.

Those who own or stay at this 500-year-old, allegedly cursed house often meet terrible fates.

A holy well supposedly infused with a saint's spirit flows within this quaint chapel.