The little-known second castle that William the Conqueror built in York.

Makers and sellers of the original and finest York Ghosts.

One of the shortest streets in York has an especially odd name.

Follow the original medieval paths that wind through this intriguing section of the city.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

The library's graceful rotunda is like a bibliophile's temple.

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

Displaced highlanders would take shelter from the wet Scottish climate under the large walled bridge at Glasgow Central Station.

This doorless 20th-century elevator doesn't stop or slow down.

The oldest garden in Prague, once part of an medieval orchard.

A turn of the century building boasting some of the most beautiful art nouveau architecture in Prague.

An Orwellian sculpture with eyeball cameras watches passersby.

The tunnel's elegant proportions keep you snug with no claustrophobia freak-out.

This automated sculpture of two men peeing will spell out text messages with their micturition.

This artificial cave looks like something out of a fairytale.

An old asylum graveyard that's been abandoned for half a century attracts those seeking a dark thrill.

Microscopic scenes; some call it novelty, some call it art.

Walk through Czech history in Prague's largest graveyard.

This Prague museum collects brutalist relics and memories from the country's former Soviet rule.

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

A collection of anatomical samples from one of the first anthropologists to suggest that humans reached North America by crossing the Bering Strait.

Countless grotesque faces stare out from this eerie Prague art wall.