One of the most photographed buildings in a city known for its Modernista architecture is an abandoned squat.

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

Barça football fans might see the insignia hidden in a church window as a divine sign.

The unexpectedly beloved remnants of a controversial thermal power plant.

Hidden beneath the streets of London is a secret subway that only carried mail.

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

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

A student driver's nightmare.

The longest hedge maze in the world.

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

A 30-acre garden inspired by the principles of modern physics.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

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

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

Banksy gives themself artistic license with this piece of London street art.

A kaleidoscopic warehouse-maze of handmade neon signs.

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

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

Half-drowned wooden stumps and stone blocks are all that remain of a Victorian landing that was destroyed by storms.

The rotting skeleton of a shoreside fun fair that was destroyed by fire and storms still haunts the Brighton ocean view.

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

Regency-era excess on the English Coast.

This antique prison is a tourist attraction with a sordid past.

A fantastic castle rumored to be the birthplace of King Arthur.