A plaque marks the site directly below the mid-air detonation of the atomic bomb over Hiroshima.

This exemplar of modernist architecture is meant to captivate and inspire students of the Cooper Union.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

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

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

A massive volcanic plug is now a protected area that hosts a number of bird species.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

This modest marker near Notre Dame identifies the very center of Paris.

One of the largest underground systems runs under Canada's largest urban center.

Breathtaking and huge 430 year old maps of Italy.

I-95's Tijuana-style celebration of kitsch at the Carolina border.

A grand Gothic Revival basilica with stained glass depictions of Montreal's religious history has only one soul resting in its crypt.

The "lovely red Vega" of the legendary record-settling pilot.

The most confusing clock in New York.

At 207 feet, one of the world's longest continuous escalators.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

American involvement in World War I officially ended in 1921 in New Jersey, three years late and thousands of miles from the battlefield.

Where the embers of the Big Bang were first detected.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

The rusting remains are visible sticking out of the waters of the Delaware Bay.

World War II bunker still standing on the New Jersey beach.

Rediscovered after a century, the father of the American Navy was reinterred in something dredged up from Davy Jones’ locker.