Largest Roman Catholic church in North America.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

An original apothecary from 1792.

A former major munitions plant that has been converted into a sprawling art space.

This beloved Baltimore spot features caged dolls, a giant Pez collection, and many, many mannequins.

A museum dedicated to exhibiting remarkable outsider art.

This enormous censer uses a pulley system installed over 400 years ago.

A field of nothing but boulders which resembles a giant's gravel driveway.

A tradition unlike any other, this marks the site of the annual Groundhog's Day tradition.

When the Austin Dam failed it destroyed much of Austin...and then it failed again.

This demolished goliath of American industry once loomed over the depressed town it once made thrive.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

Outsider art meets paleontology at this roadside reptile repository.

This dramatic rail curve was once the target of a failed Nazi attack.

Built in the 1970s, this curious modular home found new life as a sundae-shaped ice cream stand.

An abandoned stretch of highway, deteriorating next to the operational one.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

The most loyal of little dogs, or a Victorian era publicity stunt?

The final resting place of soldiers' loyal canine companions.

Built for the 1962 World Cup, this fully functioning botanical clock is still ticking.

A museum founded to reflect on and remember the human rights abuses under Chilean dictator Augusto Pinochet.

A record-breaking pool that uses computers to turn ocean water into cleaner, private swimming water.