The notorious "Hanoi Hilton" where Vietnamese colonial subjects and later American POWs, including John McCain, were imprisoned.

Life-sized painted illusions let pedestrians blend in with the street art.

Home of the unusual art of water puppetry, one of Vietnam's oldest curiosities.

Monument to a brutal, ineffectual US bombing campaign and a sobering reminder of the human cost of the Vietnam War.

Twice a day a speeding train passes only inches from the homes of this residential neighborhood.

A gift from the Soviet Union in the 1980s, this is the only statue of the Soviet dictator in Southeast Asia.

The first mechanized factory in Spain is also one of the most significant mints in the history of money.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

These "mermaids" that surround a plaza in Segovia are rather sphinx-like.

A curious memento mori hangs in the magnificent Cathedral of Segovia.

A somewhat mysterious biomedical museum housed inside a Spanish university.

Seaside ruins of a settlement that date back to the first century B.C.

Thanks to an acoustic anomaly, this unassuming stone bench has heard one hundred years of secrets.

This enormous censer uses a pulley system installed over 400 years ago.

The mysterious remains of a martyred teenage saint are venerated inside a small country chapel.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

The medieval castle built as headquarters for the Pope's secretive Knights Templar.

The Roman city was the birthplace of various emperors and is home to one of the empire's most impressive architectural feats.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

The world's first electric battery-powered submarine.

An impressive display of ships and artifacts from the ancient Mediterranean maritime trade.

An ancient Roman theatre restored to its former glory in the Spanish city of Cartegena.

A well-restored ancient archaeology site gives a real feel for life during the Roman age.

Legends surround this natural rock formation that looks like a Moorish king wearing a crown.