These "50 Fortresses" have been unearthed in the ancient oasis of Khwarezm.

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

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

An 18-meter-long sarcophagus of a constantly growing dead prophet.

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

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

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

The largest Lenin statue in Central Asia was moved to an empty field rather than being destroyed.

This dark, damp, perilous tunnel is the only passage from north to south Tajikistan.

Where the father of Persian poetry is laid to rest.

This ancient Silk Road outpost overlooking the Wakhan Valley is miraculously still standing.

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

Extremely isolated Silk Road caravanserai in the middle of nowhere.

This village was once a thriving Soviet uranium mining center, but is now semi-abandoned and desolate.

This retro, UFO-like structure is a remnant of the Soviet-era circus.

Lonely minaret stump of a destroyed city.

A boulder carved into the shape of the cosmonaut's head.

This mysterious complex of abandoned yurts and fading murals was meant to be a center of science and spirituality in Kyrgyzstan.

Nicknamed Kazakhstan's Grand Canyon, this natural wonder lies east of Almaty near the Chinese border.

Submerged trees jut ghost-like out of an idyllic turquoise mountain lake.

The 20-mile causeway that separates the Netherlands from the sea.

This historical Netherlands fortress still bears the marks of its single siege.

Rotterdammers' dirty minds gave this Santa a dirty nickname and cursed it to a life of wandering.

These slanted cubic abodes are a creative if odd solution to a zoning pickle.