A clumsy-looking flying locomotive rusts within sight of a busy rail station.

The unusual clock on this 18th-century market building has an extra minute hand for "Bristol time."

A closed London rail station created to cart away the dead still bears the marks of attempts to make it less morbid.

This lovely little burbling creek is actually a deadly waterway that has dragged down everyone who ever set foot in it.

This nondescript building hides an entrance to an underground nuclear tunnel system.

The abandoned funicular tunnel was a secret base for the BBC during World War II.

The designer of this railway tunnel added a birthday present for himself.

There are hundreds of secret WWII bases hidden in British forests. Built to fight a Nazi invasion, they remained unknown for decades.

The commemorative stone column conceals a secret laboratory.

An architectural oddity hides in plain sight on this iconic London bridge.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

On a site with a long military history, a 1980s shelter.

A labyrinthine underworld of tunnels and caverns hides beneath the city.

Go deep down into the earth to experience the world of Welsh coal miners.

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

Fantastically decorated underground chambers built in the 1760s.

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

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

A Victorian Fort built into the chalky cliffs that overlook the English Channel.

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

A breathtaking flower tunnel bursts with beautiful golden blossoms.

One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

A group of committed locals restored this centuries-old windmill to its original condition.