Medicinal spa created with the discharge from a geothermal energy plant.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

This architectural beauty is the home to a personal collection of more than 600 examples of mechanical musical instruments.

One of the few places in Portugal where the Celtic ritual of wearing large wooden masks is still practiced.

Men in rubber-soled boots serve as your "brakes" on this toboggan ride Hemingway described as "exhilarating."

A stunning 18th-century site where pilgrims ascend by a series of punishing stairs only to return via funicular.

An early work of the architect Álvaro Siza Vieira, these swimming pools blend into the beach.

Perhaps the most spectacular grotto along the Algarve coastline.

Picturesque intersection of witchcraft and ancient Christianity.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

Ring the bell to enter a bar that looks equal parts museum and old curiosity shop.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

Houses are tucked between, on, and underneath giant boulders.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A mysterious pillar in an ancient burial chamber is said to predict how long you have to live.

This beautifully deceptive waterfall is something far different from what it appears to be.

A New York–based physician returned home to Spain to build his own elaborate monument to Christopher Columbus.

This home designed for chocolate magnate Antoni Amatller is an exquisite treasure-box of Catalan Modernism.

Stop by, and you'll receive a map to two well-preserved ancient petroglyph sites.

The grotto where Saint Ignatius of Loyola lived as a hermit for nearly a year.

Tour the inside of a massive lava tube formed during a 1949 volcanic eruption.

The prolific artwork of a self-taught sculptor.