This unique architectural wonder is also tied to one of the 20th-century's most renowned writers.

This little-known national museum houses over 40,000 works of art from across the world.

A 19th-century mansion houses the largest collection of gin in the European Union.

Located in the thermoelectric factory that once powered the entire city, this Portuguese museum is shockingly fascinating.

This gaping hole in the middle of a remote mountain lake looks like a portal to another dimension.

This small chapel is built of human bones and decorated with a golden skeleton.

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.

Occupied for six centuries by Franciscan Order nuns, this monastery is an amazing ode to Catalán Gothic architecture.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

Mountain where Jesus was first tempted by the Devil.

This cemetery features modernist statues as strange as its name.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

Pagan monument converted to Christianity with the population.

A museum dedicated to one of Portugal's most celebrated writers.

This now abandoned restaurant provides some of the most amazing views of Lisboa.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

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

The crumbling ruins of an abandoned 12th-century monastery.

This once-forgotten oasis in the middle of Lisbon was first created over a century ago quite by accident.

The verdant mossy ruins of a Franciscan monastery lie in the remote Sintra hills awaiting exploration.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

A meow-velous tribute to a beloved street cat, made famous on the internet.

This crucial gathering spot along the "hippie trail" still displays old notes between traveling beatniks and backpackers.