Climb to the top of its spiral spire for spectacular views of Copenhagen.

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.

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.

An industrial relic is now one of Europe's most staggering art spaces.

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

Retirement home for giant obsolete machines.

Deep in the Thar desert, a temple crawling with thousands of holy rats.

This pre-Hispanic apartment complex also includes ancestral paintings that point to its military past.

Dating back to the second century, vestiges of prehispanic mural paintings are found in this underground palace.

Once home to an aristocratic family and a workers' organization, this intricately tiled building now houses a chain restaurant.

This incredible college library is a visual masterpiece of mosaic art. It also looks kind of like a giant boombox.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

Elevated freight railway turned wildly successful urban park.

The home of the first American-born saint is one of the only curved buildings in New York.

Try not to get slimed in Tribeca.

One of the most enjoyable bits of history at Coney Island and “the most romantic ride in the world.”

An island graveyard with spectacular views of the Caribbean.

Beach instrument turned bed and breakfast.

These enigmatic columns tower over the ruins of an ancient Toltec city.

These haunting ruins of a 700-year-old Prehispanic city have witnessed centuries of wars and massacres.

An Aztec temple, the largest man-made pyramid in the world, sits buried in earth with a Spanish church set on top.

An elaborate Mayan city shrouded in alien conspiracy revealed the tomb of Pacal the Great.

The ruins of an ancient Mayan city, beautifully preserved and only accessible by boat.