An acoustic anomaly with a mysterious cause.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

The magical, mossy forest that inspired Princess Mononoke.

This geothermal hot spring hides beneath a slowly growing mineral dome.

If drivers cross the rumble strip on this stretch of Route 66 at just the right speed it plays "America the Beautiful."

The hidden lair of an alchemist rediscovered in a 2002 flood.

A curious collection dedicated to human and animal anatomy and pathology.

This knobby, drooping New Orleans oak is a favorite place both for climbing and for meeting giraffes.

Florida might be at its most surreal in this museum devoted to the famed Spanish artist.

Left untouched since a double murder-suicide in the 1960s, Los Feliz murder mansion remains a neighborhood mystery.

One part local history, 99 parts gruesome haunted house.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

A monument to the art of slicing people open.

Ruins of a German Castle on top of a towering stone pillar.

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

Each year these high desert hills are absolutely covered with poppy flowers in a surreal show of nature.

The largest self-built castle in the U.S., six decades in the making.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.

The world's longest known cave system.

Behind this beachfront shop lies a spectacular, colorful sea cave with an equally colorful past.

The real life Hobbiton, this sheep farm has been forever transformed since being built for The Hobbit film series.

Every autumn, this hillside is ablaze with red summer cypress.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."