Once an indicator of social class, the color blue has come to define this city on the edge of the Thar Desert.

More than half of this Indian palace is drowned but it looks all the more spectacular for it.

The home of the Dead Sea Scrolls is an abstract modernist dream.

These numerous Israeli caves were dug out over hundreds years for reasons ranging from hideouts to burial sites.

In a small town outside Jerusalem, a roadside diner is devoted to all things Elvis Presley.

This hidden museum examines the complex history of the country's law enforcement.

These barriers stand as stark reminders of Northern Ireland's troubled past.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

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

Engineering ingenuity during the battle of Gibraltar.

Single runway interrupted by a busy road that cuts across its middle.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

The devil-defying mark left by a saint as a boy is visible inside Lisbon's cathedral.

The former Nazi Germany concentration camp stands as a museum to remember this dark chapter in European history.

The world's most active stratovolcano is almost always erupting.

Milan's duomo is covered in beautiful carving including a curious "dinosaur-like" beast.

The secret medieval communication system will whisk your words above the noise of the crowd.

Built over an abandoned train yard, this hidden gem is full of winding paths and offers gorgeous views of Sydney Harbour.

An ancient necropolis of magnificent tombs.

Niagara Falls holds a special place in Nikola Tesla's history, so they put a statue on it.

This historic fort spans more the 300 years.

Built on the remains of one the Incas’ most important gathering spots, this square keeps the spirit of a fallen empire alive.

These steeply terraced ruins are a stop along the Inca Trail to Machu Picchu.