The only castle in North America to ever house European sovereigns.

The museum chronicling a treasure hunter's dream, fulfilled.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

"We Seceded Where Others Failed."

A monument celebrating the idea of reaching inaccessible places.

The lesser-known cousin of the Great Pacific trash island.

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

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

Antarctica's bustling metropolis, originally established by Richard E. Byrd.

The place of worship erected not once, but three times in one of the most desolate places on Earth.

A wooden hut from the Heroic Age of Antarctic Exploration.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

The former home of the Nobel Prize-winning American writer is now home to dozens of six-toed cats.

Museum preserving torture methods from the past.

An enormous pink granite batholith, long attributed with spiritual powers by the Tonkawa Indians.