A subterranean playground in an abandoned slate mine.

The elaborate clockwork contraptions in this Scottish gallery create small worlds of whimsy and horror.

A historic London pub with prison cells in the cellar and a "spy room" on the second floor.

A Victorian natural history and ethnographic museum with wonderful turn-of-the-century, science-book-esque evolution displays.

A 18th century graveyard and its astonishing cortege of macabre iconography.

This series of Scottish caves has no clear purpose other than baffling historians.

England's oldest surviving hedge maze has been confusing visitors for over 300 years.

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

360° views of the city plus five floors of optical illusions and hands-on science.

The sign at the garden gate reads: "These Plants Can Kill."

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

A spectacular rainbow of stained glass makes the "Pink Mosque" one of the most beautiful in Iran.

Created as a coal reserve, it is today a natural park with stunning wildflowers, ancient marine fossils, and remnants of a 19th century mine.

An art gallery, studio, and shop that celebrates death.

Unusual finds in this shrine to local law enforcement include a 19th-century vampire-slaying kit.

Over two million dolls have been healed during this hospital's century in business.

A microcosm of the whaling industry in a small Australian town.

Australia's largest collection of rare and bizarre insects.

A remarkable lifelong collection of antiques and art preserved in a historic Melbourne townhouse.

The largest collection of Indigenous Australian artifacts in the world, and the rare museum where wood-and-glass cabinets have trumped interactive exhibits.

One of Australia's largest collections of preserved animals is on display in a historic theater.

Once housing children next to hardened criminals this historic jail once displayed Ned Kelly's skull until it was stolen.

The largest wax museum in the southern hemisphere features a grizzly chamber of horrors.

Built over an abandoned train yard, this hidden gem is full of winding paths and offers gorgeous views of Sydney Harbour.