A network of concealed passageways lies within a busy London Underground station.

A house of bones — but nobody is quite sure to whom they belong.

This medieval sanctuary's tree-framed door looks like a portal to a mythical realm.

This beautiful Victorian ironwork masterpiece was built to keep London from smelling like poop.

Below a historic English market town lies a secret underground city complete with kitchens, laundries, storerooms, and an underground lake.

Remnants of cells from the most notorious London prison may lie in the basement of a rare Victorian Gin Palace.

A historic arboretum and non-conformist, non-denominational park cemetery.

A clock designed to run with perfect accuracy for 10,000 years.

Museum about life, death, and cannibalism in the Stone Age.

English antique dealers with a taste for the unusual.

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.

The sixth of London's "Magnificent Seven" cemeteries, and a source of unlikely inspiration to Beatrix Potter.

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

An Oxford museum where visitors can have tea with the Mad Hatter and climb through the wardrobe to a fantasy land.

The remains of Crystal Palace Great Exhibition of 1851.

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

The largest of London's subterranean rivers and once a mad, bad center of London life.

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

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

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

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

A historic house left in "dramatic still life."

Hear the quietest sound from across the dome.

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