Neon artworks light up this dark Edinburgh tunnel.

The building where Mary, Queen of Scots was said to have bathed in white wine.

It's a mystery how these curious columns wound up in an Edinburgh suburb.

These steps offer a breathtaking view of one of Europe's most besieged fortresses.

This king penguin is a knighted brigadier of the Norwegian Army.

This allegedly haunted 16th-century tower house-turned-museum exhibits thousands of spectacular objects.

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.

Accessible only at low tide, the deserted island is dotted with World War II ruins.

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.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

A hidden treasure in London with a rich medieval history, and the resting place of many luminaries.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

A historic London cemetery now serves as a nature park incorporating gravestones & memorial statues.

The remains of Crystal Palace Great Exhibition of 1851.

Catacombs turned marketplace.

The curios of pharmacist and collector Henry Wellcome.

Rebuilt remains of a temple to Roman god Mithras.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

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

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

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.