The pockmarks across the building's facade are remnants of the Blitz.

This unassuming passageway played a key role in one of the most important events in U.S. history.

A secret greenspace hides atop a Capitol parking garage.

This historic structure has been used as a mosque, a barracks, a prison, a school, and a bakery.

The final resting place of the tragic king and queen of the Jazz Age is tucked away in a small Maryland graveyard.

The oldest standing Byzantine church in Athens is tucked within a monastery in the middle of an upscale shopping district.

A man's head is enshrined beneath a statue near the first building constructed for the modern Olympic Games.

The commemorative stone column conceals a secret laboratory.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

Giant pinnacles in the sun-scorched lands of Southern Utah have been nicknamed "white ghosts."

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

The oldest platform carousel built in the United States continues to delight children in Martha’s Vineyard.

A king's bloodstained shirt is among the gruesome collection of artifacts displayed below Stockholm's Royal Palace.

The U.S. Fish Commission’s effort to mass produce carp.

An overlooked memorial honoring the local Washington residents who died in World War I.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

The famous polar explorer stands outside the Royal Geographical Society's headquarters.

A small 12th-century temple surrounded by waters believed to have curative properties.

In the depths of Glasgow Cathedral's crypt, one pillar stands out from all others.

Disney World's very first waterpark is now an abandoned ruin being reclaimed by the swamp.

The first modernist church in Europe.

The 20th-century chapel’s intricate woodwork includes amazing details, most notably angels playing bagpipes.

Edinburgh's oldest statue hides within a parking lot behind the city's iconic cathedral.

A labyrinthine network of chambers with a storied past hides below Edinburgh's South Bridge.