This Cambodian riverbed is covered in ancient Hindu carvings both above and below the waters.

A former French military respite turned jungle tourism hotspot.

A battle between nature and architecture in the Cambodian jungle.

The hallucinogenic center of the ancient world.

This hunter-gatherer architecture is believed to be the oldest religious complex known.

A marvel of Byzantine engineering under the streets of Istanbul.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Perhaps the tiniest sculpture in Saint Petersburg is a little bronze finch inspired by a song.

This massive monument honors the first human in space.

Gargantuan home of Russian science.

One of the world's tallest statues is also one of its most hated.

Stalinist skyscraper built with help of cryotechnology.

The world's tallest statue of a woman wields the world's tallest sword and is at risk of toppling over.

Some Moscow residents once claimed the bizarre, contorted mass of metal on top of the building was used to manipulate minds.

Dozens of padlock-trees along the Moscow River.

The world's first museum dedicated to the work of game-changing naturalist Charles Darwin.

Hidden in a metro shop under a shopping mall, this small museum tells the story of one of the world's largest urban transit systems.

The avant-garde design was able to bypass strict Soviet regulations on architecture.

Once frequented by heavyweights of the Russian arts scene, this café is stuck in the 1800s.

World's largest bell sits on the grounds of the Kremlin in Moscow.

The tallest hotel in Europe.

An early-20th-century "dacha" village of quaint cottages curiously located in a modern part of Moscow.

Moscow's imposing monument to the Space Age.

A 250-year-old timepiece-automaton adorned with golden mechanical birds, which still sing to this day.