A sign marks where the two bodies of water meet.

Local authorities nearly destroyed this mural before a viral video rallied international support to save it.

This stucco building in North Africa was the first American-owned property on foreign soil.

Rare karst landscape eroded from a flat seabed.

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

A centuries-old house, once part of the wall of Granada, sports musket barrels from the battlements which allude to its original owner.

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

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

A haven for book enthusiasts across the street from Retiro Park.

One of Madrid's oldest trees, with a long and colorful history, resides in El Retiro Park.

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

The remains of the second-oldest zoo in Europe can be seen within these library gardens.

The remains of this misplaced church were moved here stone by stone.

Madrid's last horchata kiosk is a blue-and-white beacon of refreshment.

The only urban monument in the world designed by the great surrealist painter Salvador Dalí.

Once a resting spot for King Fernando VII.

The lengthy skeleton of one of the tallest Spaniards of all time is on display in Madrid.

Along the pavement of this neighborhood in Madrid are quotes from famous authors.

The earliest known map to show America, discovered by accident at a Paris bookshop.

This piece of early engineering is rather unknown despite its location in the heart of Madrid.

A statue commemorating a beloved stray dog who was adopted by the entire neighborhood where he lived.

One of many reminders of Tesla's scientific contributions overlooks the falls which inspired him.

A museum dedicated to the centuries-old cave dwellings that housed marginalized communities on the outskirts of the former capital of Muslim Spain.

This historic hotel preserves many treasures from its heyday hosting passengers on the Orient Express.