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

Beirut's thinnest building was the result of feuding brothers.

The largest hewn stone in history.

This modernist cinema has survived war and reconstruction to become a symbol of Lebanon’s revolutionary spirit.

Known as the "Valley of the Moon," this Jordanian wadi is one of the most amazing desertscapes on Earth.

A more chill but no less fascinating version of the famous ancient archeological site.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

Breathtaking and huge 430 year old maps of Italy.

Padlocks cover this rickety footbridge with love.

The eerie burnt-out remains of a prominent building where 30 protestors lost their lives.

The dining hall that nourishes workers in Chernobyl's Exclusion Zone is also open to visitors.

The biblical sculpture honors those who lost their lives, homes and communities to the Chernobyl disaster.

The deepest metro station in the world.

One of the largest museums in Ukraine remembers the story of the German-Soviet War in iconic, brutalist style.

This derelict superstructure was a very important warning system for the Soviet military.

340-foot statue built to honour the Heroes of the Soviet Union.

One of the most poignant ruins of the Chernobyl nuclear disaster, the local football team's stadium has been quickly reclaimed by nature.

The largest catacomb system in the world.

This attraction was abandoned after the Chernobyl disaster.

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

This ancient cave temple complex is the largest and best-preserved temple complex in Sri Lanka.

An ancient stone fortress considered by many to be the eighth wonder of the world.

Singapore's oldest Hindu temple.