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

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

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

This doorless 20th-century elevator doesn't stop or slow down.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

This artificial cave looks like something out of a fairytale.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

A Jenga-style cylindrical tower of books that appears to go on forever.

Macabre astrological automaton clock dating to the late 1400s.

A small museum filled with over 1,000 clocks, and one particular clock calibrated to run until the year 9999.

In paradise, feral pigs have claimed an island all to themselves.

A small collection of iguana-infested ruins hides amid Cancún's bustling hotel zone.

The first statue to be added to Saint Peter's Square in over 350 years is an ode to migrants and refugees around the world.

This equestrian statue of Constantine the Great has been the subject of criticism for centuries.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

These spartan apartments are provided to clergymen visiting Vatican City.

Breathtaking and huge 430 year old maps of Italy.

This ancient Roman arch misled treasure hunters for centuries.

The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.

Before it was buried by volcanic ash, this fast-food restaurant fed the hungry hordes of ancient Rome.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

In the past, Renaissance sex workers were encouraged to entice customers on this bridge.

Two stone columns flank the grand Venice square, but there were supposed to be three.