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

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

Gaze upon chocolate sculptures depicting everything from chariot races to Gaudí's famous church at this shrine to sweets.

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

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

A beautiful but toxic fountain of mercury.

This semi-secret storybook hedge maze is also the oldest garden in the city.

This wildly-tiled artist's palace is a living and growing account of the creator's life, loves, and labors.

Shakespeare, David Bowie, Dr. Who, the Saxons, Druids and Romans are all claimed to have all made their mark on these massive man made tunnels.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

A Neolithic burial site built 1,000 years before Stonehenge.

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

The remnants of a strange stilted building on rails can still be seen at low tide.

To literally keep their waste out of their own backyards, the citizens of this English city built an impressive sewer system that is still in use today.

This concept building is the UK's first attempt at making a permanent structure of nothing but trash.

The natural history museum displaying the British bird collections and dioramas of Edward Booth, free of charge.

This tunnel entrance is built to resemble a grand castle but no one is quite sure why.

This WWII aircraft museum presents its wrecks like taxidermy, complete with recreations of the crash sites.