You could be standing at the site of one of D.C.'s most fatal tragedies and not even know it.

The most accurate timepiece in the world.

Of the many chalices in the running for the Holy Grail, this one in Valencia Cathedral sure looks the part.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

This attraction is part anthropological journey and part amusement park.

Brightly colored 30-foot-tall totems light up the desert sky just outside Las Vegas.

A bas relief commemorates the "Nuns of the Battlefield" who cared for soldiers on both sides of the conflict.

Ho Chi Minh's perfectly preserved body has been on display here since 1975.

Home of the unusual art of water puppetry, one of Vietnam's oldest curiosities.

A giant open-air sculpture made of over 200 full-sized boats.

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

The Citrus Variety Collection at UC Riverside contains two trees of each of the 1,000+ varieties of citrus.

The "world's biggest dinosaur" once housed a creationist museum in its abdomen.

Yo, Adrian!

Huge masonic hall in Philadelphia with lavishly themed rooms.

A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

After a nearly successful attempt on Hitler's life, the conspirators met their fate in the courtyard of this Berlin building.

The celebrated eyesore created by starry-eyed sweethearts.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.