This beautifully restored fortification kept the city safe for centuries.

Groups of prehistoric tombs that dot the mountains of northern Oman.

A sinkhole and now a swimming hole, too, full of dazzling turquoise water.

This indoor ski resort has a mountain contained inside a mall.

This ducal residence was once home to a future Russian empress and a French king in exile.

The reconstruction of this prominent building fulfilled a long-written command.

A top secret Cold War bunker hidden beneath a Latvian spa facility is now open for tours.

Latvia's symbolic mountain-shaped national library is home to millions of cultural tomes.

The oldest housing complex in Riga is a mini timeline of architectural trends.

A former Latvian headquarters of the brutal KGB secret police is now open as a grim reminder of their atrocities.

3,000 market stands in five former Zeppelin hangars.

The monastery survived the Communist revolution in Mongolia as a religious museum.

Established hundreds of years ago, Gandan remains the premier Buddhist monastery in Ulaanbaatar.

Dinosaur eggs were first discovered at these fiery red cliffs.

A huge communist-era propaganda monument and mural that offers stunning views of the Mongolian capital.

Enormous statue of the Emperor of the Mongols.

Controversially restored in the 1970s, this giant 15th-century mosque is shrouded in legend.

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

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

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.

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

This striking, historic hotel has major Wes Anderson movie energy.