The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

5,000 skulls in memorial to those killed by the Khmer Rouge.

A nightmare for the claustrophobic lies hidden in Southeast Asia.

Khmer Rouge's high security prison.

Giant pagoda houses the car that drove Thích Quảng Đức to his death by self-immolation.

Ha Long Bay's "Cave of Surprises" houses a popular phallic rock formation.

Climb to the top of the world's largest seated bronze Buddha.

This historic island prison holds one of the dungeons from the Count of Monte Cristo even though it is a work of fiction.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Ancient snack bar of the Roman Empire re-opened.

Erotic art covers the walls of the largest ancient pleasure palace.

Pompeii's less famous neighbor is still revealing her secrets.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

The legendary cliffside castle of three-time Voivode of Wallachia, Vlad the Impaler.

This ancient Irish tower could easily have stood in for Rapunzel's prison.

Ancient Bronze Age rampart that was used into the middle ages.

Carvings in Turkey's Marble Road may have directed ancient Romans to a hidden brothel.

The alleged house of the Virgin Mary is tucked away in a park and nature preserve on Mt. Koressos in Turkey and is holy to both Catholics and Muslims alike.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

A Bronze age settlement on the Greek island of Santorini might have been the inspiration for Plato's Atlantis.

This snug medieval lane is one of the narrowest streets in the world.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

One of the largest underground systems runs under Canada's largest urban center.