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

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

The commemorative stone column conceals a secret laboratory.

The bridge is a secret gallery of discarded gum that has been transformed into miniature masterpieces.

Largest lake in Great Britain measured by surface area.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

Ancient cliffs resembling a kilt on Scotland's second largest island emit an entrancing sound.

An ancient Scottish rock formation said to be the gravesite of a giant remains ensconced in legend and intrigue.

This single-track road rewards brave drivers with stunning Scottish scenery.

The true age of this ancient stone circle is unknown, but its stunning vista isn't in question.

The discovery of this Neolithic settlement, which contained a Stone Age "cathedral," threw archaeologists for a loop.

A red sandstone freestanding monolith rises out of the sea in northern Scotland.

Possibly the oldest of Britain's ancient henges is also one of its most stark.

The most northern place on the mainland of Great Britain.

The sign marks one of the endpoints to mainland Britain's longest overland travel route.

A castle in the Scottish Highlands has been continuously inhabited since the 1300s.

This Scottish castle has witnessed clan rivalries, Jacobite uprisings, whisky smuggling, and more.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

Hear the quietest sound from across the dome.

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

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

Eighty million natural history specimens call this gargantuan museum home.

Northern Ireland's Brobdingnagian stepping stones.

The atmospheric road was never meant to be so creepy.