What was meant to be a temporary exhibit is now a permanent fixture at the St. Louis Zoo filled with beautiful birds.

Dr Barnes' $25 billion private collection of art and arboretum.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Tiny memorials honor individual victims of the Holocaust.

The maze-like transportation hub contains abandoned areas, derelict stores, and a resident bat colony.

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

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

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.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

A daily replay of the experiment that proved the rotation of the Earth.

A tour de force of a fountain, memorializing a man who loved fountains more than anything else.

This daunting 1st century fortress was purportedly the site of one of the most dramatic revolts of the Jewish-Roman wars.

Mesoamerican monoliths and zoomorphic stones covered in royal visages, ancient mythology, and grand celestial events.

This tree was extinct for a thousand years before sprouting again from a 2,000-year-old seed.

Known as the "Cross At The Crossroads," this massive metal cross is just short enough to avoid the FAA.

Oldest existing wire suspension bridge in the United States.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

Fresh wooden posts have been added to ancient holes to recreate a primitive henge clock.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

When you visit his grave, be sure to rub the Great Emancipator's nose for good luck.

A real flying saucer, contracted by the U.S. Air Force.

The largest clock face in the United States is twice the size of Big Ben and infinitely more ad-sponsored.