Rare recess caves fill this unbelievably beautiful Ohio park.

A museum filled with tiny, adorable versions of the mighty Royal Danish Navy.

The art museum is decorated with creatively remodeled pre-Nazi swastikas.

Tiring of digging out the door to this church for every service, it was eventually abandoned to the sands.

A perfectly circular stronghold constructed in the 10th century is now a nucleus of Viking culture housing a museum, village, and reenactment of an epic Viking battle.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

Vortex-shaped aquarium hosts Europe's largest school of piranhas and other ocean creatures.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

Copenhagen's celebrated theme park and gardens.

Once thought to be the oldest living tree in the world, Methuselah was germinated before the Egyptian pyramids were built.

Quite simply the largest tree in the world (by volume).

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

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

The original home of the Lego has a huge amusement park dedicated to the iconic plastic toy.

The Old Courthouse takes visitors on a captivating trip through St. Louis' timeline.

A creepy sculpture of a decapitated head invites viewers to see St. Louis through its empty eyes.

The first rural cemetery west of the Mississippi is home to the elaborate tombs of St. Louis' local beer barons.

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

This titanic oil company sign is a reminder of the Americana boom of the 1970s and also its commoditization.

This bridge uses an inverted bowstring truss and is believed to be the only of its kind in the United States.

The largest ancient burial mound in Ohio.

A symbol for the opposition to nuclear power around the world.