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

Many people don't realize there’s a lot going on in—and below—the world’s tallest triumphal arch.

If you can look past the nearby sewer pipes, this urban sinkhole grotto is a mini-paradise.

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

Clap your hands at the base of the pyramid, and the song of a sacred Mayan bird will echo through the air.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

Every equinox this Maya pyramid puts on a spooky ancient light show.

Only a fragment of this 15th-century Dance of Death survives today.

Relics from an era long gone, sit idle outside this Estonian museum.

This striking memorial is one of Estonia’s most controversial Soviet leftovers.

The oldest church in the Estonian capital is home to over 100 fantastical cemetery coats-of-arms.

Germany's Glienicke Bridge has a shady history of clandestine meetings, espionage, and spycraft.

Hitler's bleak vision of relaxation still stands as a mostly abandoned 10,000-room resort complex.

This enchanting mountain plateau celebrates spooky local folklore.

The site of a concentration camp where inmates were made to take part in one of the largest counterfeiting operations in history is now hauntingly empty.

A former ironworks that was the first UNESCO industrial site.

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

The "Prussian Versailles" that is as glorious today as when it was built.

A quaint Russian village in the middle of a German metropolis.

Explore the complex ecology of this multifaceted nature preserve by riverboat.

Home to 10,000 medical specimens including the remains of Rudolf Virchow's extensive collection of pathological specimens.

This historic stone bridge has an entire neighborhood clinging to its sides.

The fairy tale castle of the "fairy-tale king."

This little replica of Lady Liberty provides a bit of NYC in a Japanese city.