The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

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

If you visit Santa's village, you can get your passport stamped to show you crossed into the Arctic Circle.

A Spanish town built into the cliffs.

One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

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

This pub was 238 years old when it decided to revamp its image: It started serving Thai food.

This unique bridge curls up like a caterpillar to let boats pass and then unfurls again to span a small canal.

This 16th-century house tells the city's history through old artifacts and quirky tales.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

A network of ancient Egyptian tombs built into the cliff face along the Nile.

One of its engravings is believed to be among the first representations of medical and surgical instruments.

The largest known Ancient Egyptian obelisk.

Ozymandias’ time-keeping temple.

These Egyptian statues have survived for 3,400 years and were an acoustic wonder of the ancient world.

This unassuming tree stump reportedly traces its roots to the famous pharaoh queen's reign.

A quirky bookstore hidden beneath a sea of whitewashed Greek villas.

This black sand beach was crafted from volcanic explosions including the historic Minoan eruption.

Rebuilt several decades ago, its striking murals prevent it from being reconsecrated as a church.

One of the largest mines in Bulgaria is now home to a vast museum more than 100 feet underground.

A collection of art from Bulgaria's time as a communist state.

This is the largest cemetery in Ireland and the first cemetery museum in the world.

A nun spent 16 years painting the stunning Celtic mural that covers the interior of this WWI memorial.