The London Underground is one of the oldest metro systems in the world.

The Sahara Desert stretches across northern Africa.

The Golden Gate Bridge spans the entrance to San Francisco Bay.

The shortest commercial flight in the world operates between two Scottish islands — Westray to Papa Westray — lasting about 90 seconds.

The Great Wall of China is not visible from space with the naked eye — it's too narrow relative to its length.

In Switzerland, it is illegal to own just one guinea pig — they are social animals and must have a companion.

The Colosseum in Rome could hold up to 80,000 spectators — comparable to a modern NFL stadium.

Urban populations now exceed rural populations worldwide.

The Burj Al Arab is built on an artificial island.