The original vault that held the president's remains still stands, empty, not far from where he was finally buried.

You can walk through the first Boeing Air Force One, which famously carried JFK's casket from Dallas back to D.C.

A quiet, gothic haven nestled between Pittsburgh's Squirrel Hill and Point Breeze neighborhoods.

This innovative steam machine was no doubt the most famous of the pioneer locomotives.

The massive machine creates cracking displays of indoor lightning.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

Ship-sized kinetic sculptural fantasy.

London's Victorian Tower of Babel.

The broken skateboards that became a poignant memorial to a murdered skater.

London's smallest police station is barely the size of a phone booth.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

The sounds of the world's largest fully functioning pipe organ dazzle shoppers at a Philadelphia Macy's.

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 Germany 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.