An underground world of gorgeous, palatial metro stations designed as a nuclear shelter complex.

This "tower of death" has acted as an observatory, a religious hub, and an executioner's lair.

Ancient barriers wrap around what was once an important stop along the Silk Road.

Light still pours into the ruins of this ancient Islamic observatory.

The Avenue of Mausolea is a series of grand palatial tombs.

The world's second-tallest flagpole stands proud despite dropping rank.

The remains of an ancient city-state along the Silk Road.

Where the father of Persian poetry is laid to rest.

A building facade covered with the statues of 11 giants of Tajik literature.

Extremely isolated Silk Road caravanserai in the middle of nowhere.

This quaint mortuary chapel hides a stunning Celtic Revival and Art Nouveau interior.

This 19th-century monument served an important purpose for fishermen thanks to its built-in barometer.

The anatomical-pathological collection of a man who changed surgery.

The gloomy ruins that inspired Bram Stoker to bring Dracula to life.

Scattered throughout London are ancient remnants of the city's former bounding wall.

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

A Victorian natural history and ethnographic museum with wonderful turn-of-the-century, science-book-esque evolution displays.

400-year-old garden, restored to beauty.

After nearly 60 years, there's still a bear at Paddington Station looking for help.

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

The remains of Crystal Palace Great Exhibition of 1851.

Hear the quietest sound from across the dome.

In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.

Spend the night in this formerly abandoned traditional Scottish village.