A historic London pub with prison cells in the cellar and a "spy room" on the second floor.

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

London's smallest police station is barely the size of a phone booth.

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

The signs of a long buried road can still be found hidden beneath a London sewer grate.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

The anatomical-pathological collection of a man who changed surgery.

This tangled English forest looks like something right out of a fairytale.

The fountain marks the area where hundreds of accused witches were burned at the stake.

A historic house left in "dramatic still life."

The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

"Respectful to the dead, safe and sanitary to the living, dedicated to the Genius of Memory..."

This castle was established by the 4th Duke of Montrose and is connected to the Buchanan Clan.

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

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

Wedged between two buildings at the Great Ormond Street Hospital is this secret music installation.

Amazing and mysterious Neolithic settlement on Scotland's Orkney Islands.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.

A vast overgrown cemetery, once known as one of London's "Magnificent Seven."

A hands-off space for graffiti artists to hone and display their skills.

The curios of pharmacist and collector Henry Wellcome.

The longest hedge maze in the world.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

One part local history, 99 parts gruesome haunted house.