An alleyway plaque is all that remains of the independent Texas' envoy that forgot to pay their rent for over a century.

Hear the quietest sound from across the dome.

A makeshift shrine to the late rock star is still kept up on the nondescript façade outside 1 Logan Place.

Catacombs turned marketplace.

The curios of pharmacist and collector Henry Wellcome.

Rebuilt remains of a temple to Roman god Mithras.

An unusual round church in London with a Templar past.

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

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

A student driver's nightmare.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

Eighty million natural history specimens call this gargantuan museum home.

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

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

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

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

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

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the first ‘Harry Potter’ film.

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

Rebuilt several decades ago, its striking murals prevent it from being reconsecrated as a church.

Rock carving created 1,300 years ago 75 feet off the ground.

A gigantic statue of a Russian soldier watches over the ancient city of Plovdiv, a prominent reminder of the Soviet period in Bulgaria.

Mysterious standing stone formations looks like a petrified forest.

A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.