An underground city of salt.

Real bones which are said to have belonged to a Polish dragon.

Italian cave with exceptional acoustics and an unsavory history.

The ancient latrines of the Greeks, in all their public glory.

Ancient serpentine sacrifice holder that has stood the test of time.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

The longest hedge maze in the world.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

A historic arboretum and non-conformist, non-denominational park cemetery.

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

A museum wholly devoted to juvenescence.

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

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

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

The remains of Crystal Palace Great Exhibition of 1851.

Amazing collection of folly buildings in Cobham, Surrey.

Angels, demons, and tortured souls on a giant wall mural in a little church.

Gothic tower where Lord Alfred Tennyson wrote the poem "The Sleeping Beauty."

Hauled from the water's depths, Henry VIII's flagship is preserved in this capsule-shaped museum.

Climb inside an iron crystal magnified 165 billion times its normal size.

From Tintin to the Smurfs, Europe's greatest graphic icons are celebrated in a grand Art Noveau gallery.

A little sculpture with a large wardrobe.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.