A 2000-year-old Roman amphitheater lies just below Guildhall Yard.

The largest greenhouse in the world is home to over one million types of plants.

An incarceration museum on the spot of possibly the oldest prison in England.

Eighty million natural history specimens call this gargantuan museum home.

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

Tiny effigies of the victims of Edinburgh's famous Anatomy Murders.

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

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

The site of London's first coffee house has been serving refreshments of one kind or another for 360 years.

A mysterious artist-run cabinet of curiosities and library.

Remnants of a Victorian garden feature sitting in public woodland.

A historic house left in "dramatic still life."

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

A church that bred legends, and served as an inspiration for the Da Vinci Code.

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

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

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

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

In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.

Surreal riveted sea forts once protected the Kent shores from German attack.

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

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

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

Hear the quietest sound from across the dome.