One of the three perfect vellum copies of this historic book known to exist is on display in a specially-designed case.

The legacy of a wealthy executive and his wife, this little-known art museum features works by Picasso, Monet, Renoir, Cezanne, and more.

Once a sewer culvert, this road tunnel now offers cyclists and pedestrians a subterranean stroll under the C&O Canal.

Also known as the Founding Church of Scientology.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

A haunting tribute to pioneering photographer Clover Adams.

The national park was once a plantation estate.

The oldest continuously operating fish market in the United States.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

Engraved in stone here are the signatures of everyone who signed the Declaration of Independence.

Though it was originally dedicated to the Hindu god Shiva, Baphuon was converted to a Buddhist temple in the 15th century, complete with a massive hidden statue.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

This is the oldest Roman-made bridge in the city still existing in its original state.

A hospital where antique dolls are given new life.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

A memorial in the Tiergarten is a reminder of the suffering inflicted on homosexuals by the Nazi regime.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

Monks turned this mountain into a temple by digging grottoes, tunnels, and a huge pagoda-like hall.

A son-and-daughter meat market, hawked by mom and dad.

The once highest point in China blends symbolic design with a kick of adrenaline.

This enormous gold Buddha statue was hidden inside a stucco decoy for centuries.

Bangkok celebrated its shifting monarchy with a militaristic homage to democracy.

Since 1947, this living history museum has been providing an immersive look at life in Plymouth Colony.