Ornate limestone building now filled with geologic specimens, and more.

The world's largest anatomically accurate brain sculpture.

If astronomy had a ghost, it would look like this observatory.

The only freestanding table rock formation east of the Mississippi.

The chiseled jaw of this forgotten American hero still stands tall in a small Indiana town.

The longest navigable underground river in the United States is home to countless blind and albino animals.

The former textile factory is now an oasis for the arts.

The world's longest known cave system.

Found down a long dirt road, a sacred Mexican cenote and 18th-century hacienda remain hidden.

These azure waters were thought to lead to the Mayan Underworld.

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

A magical sinkhole on the Yucatán Peninsula is adorned with mini waterfalls and hanging vines.

This unique collection collects pieces of art etched into thin pieces of stone.

This bridge is embedded with a giant steel dragon that breathes fire from its mouth.

Vietnam's feral abandoned water park offers access to a post-apocalyptic funscape, now with fewer crocodiles.

World's largest cave was only discovered in 1991, and now offers tours to the public.

Giant pagoda houses the car that drove Thích Quảng Đức to his death by self-immolation.

Sacred Buddhist home of some spiritual monkeys.

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

Romania's triumphal arch looks out over Bucharest.

A stunning 18th century pharmacy and medieval chemist's collection.

The legendary cliffside castle of three-time Voivode of Wallachia, Vlad the Impaler.