Built on a medieval synagogue, this church has a burial crypt, tunnel system, and Jewish ritual bath hiding deep underneath.

Italian cave with exceptional acoustics and an unsavory history.

An otherworldly alpine pasture with its own unique microculture that recalls Middle Earth.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

This only museum in the world dedicated solely to mushrooms.

This modern, multimedia museum takes visitors on an evolutionary journey back in time.

This scale model of our solar system hid in plain sight for years before a physics team sought out all the planets.

The remains of a sunken military ship wreck visible through clear water.

An eclectic art form practiced by untrained masters is celebrated at this museum in the heart of Zagreb's old Upper Town.

Once a state-of-the-art tuberculosis treatment spa, these ruins are now ruled by paintball players.

A peculiar museum that includes many drunken tales, a drunk driving simulator, and much more.

A wunderkammer of mysterious objects and stories.

This castle was established by the 4th Duke of Montrose and is connected to the Buchanan Clan.

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

Amazing and mysterious Neolithic settlement on Scotland's Orkney Islands.

Perfectly preserved ancient monastery in an impossibly dramatic location on a rocky island in the Atlantic.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

The world's only museum devoted to the wonders of fluorescence.

These fantastically named natural pools look like something out of a Scottish myth.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

Most-visited and most-photographed slot canyon in the American Southwest.

Sleep in a glass pod dangling off a cliff.