These imposing walls and towers look more like the ruins of a fortress than a monastery.

The oldest inn in Kilkenny was established by the first convicted witch in Ireland.

Local legend says the remains of Father Christmas lie within the medieval grounds.

A tongue-in-cheek arcade where the games are based on everyday life.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

Winding paths and ramshackle mausoleums in the oldest "park cemetery" in London.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

A kaleidoscopic warehouse-maze of handmade neon signs.

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

A once grand hotel now sits eerily abandoned in the Catalan countryside outside Barcelona.

One of Europe's largest supercomputers is housed inside of a disused chapel.

Turntable anonymously received orphans, alms, and groceries.

A stately palace has been converted into the world's largest cannabis museum.

Bask in the 19th century grandeur of an eccentric Freemason millionaire's private gardens.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

This charming candle shop has been in business since 1789.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

The remains of the second-oldest zoo in Europe can be seen within these library gardens.

This lucky bronze frog was gifted to Madrid by a casino.