This Rhode Island mansion was a stand-in for the exteriors of Collinwood in the original "Dark Shadows" series.

You can row a boat through this ancient underground reservoir.

Disused seaplane hangar gets a second life as the jaw-dropping home of Estonia's museum of maritime history.

A restored Pittsburgh house of God has been converted to a marvelous house of suds.

This former coal gasification plant found a curious second life as a popular public park.

A 19th-century subterranean reservoir repurposed as a contemporary art cave.

A boiling wellspring flowing with natural gas burns in a continual blaze.

A natural gas leak provides a flickering flame beneath a waterfall.

These hellish-looking cliffs in the Canadian Arctic have been burning for centuries.

Flames have been burning within this mountain for more than 2,500 years.

A shrine of fire worship built on top of a natural flame.

Mysterious hillside with a continuously burning natural fire.

Modern art meets modern convenience in possibly the world's most architecturally important public bathroom.

There are two legends behind the origin of this unusually tall sanitary structure.

Hidden in one of New York's oldest subway stations is the final remnant of the site of the bizarre Shakespeare Riots.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

This abandoned subway station can still be seen on regular commuter trips.

“Live hard, ride fast, eat pizza” at this joint filled with Evel Knievel memorabilia.

This bar hosts an ever-evolving napkin art installation devoted to an American president.

Transport yourself to the 1980s era of video games at this themed restaurant and bar.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

This legendary urban waterfall creates a dazzling display of rainbows.

It should come as no surprise that the best view of the Hollywood sign is from Batman's lair.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.