This ominous Albanian fortress houses tanks and downed planes as a reminder of their victories over Western imperialism.

A medieval bridge stretches over a sulfur-rich river that leads to year-round natural hot springs.

Once the fallout shelter of a dictator, this sprawling bunker is now a combined history museum and contemporary art gallery.

An Albanian monument to the Communism that nearly crushed the country is now a crumbling wreck.

In the heart of Tirana, this underground nuclear bunker has been transformed into a museum.

This medieval manor house was equipped with secret compartments for hiding priests.

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

One of the world's largest collections of pathological specimens.

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

This coffee shop lies hidden beneath a historic church.

Winding paths and ramshackle mausoleums in the oldest "park cemetery" in London.

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