This crumbling Portuguese ruin overlooks the populace it once ruled.

One of the smallest bookstores on the planet.

Iron Age runes and ruins hide in plain sight along this Portuguese beach.

Considered the birthplace of the Copper Age and Bronze Age, the river is tinted red from 5,000 years of mining.

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

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

An abandoned mine now resembles a post-apocalyptic landscape of derelict buildings and blood-red pools of water.

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

At night, bats patrol this magnificent 18th-century space in search of book-eating pests.

A unique seaside cave where Aleister Crowley faked his own death.

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

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

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