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

A hidden three-foot-wide house separates these two regal churches.

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

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

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

A garden in Lisbon filled with giant porcelain creatures.

The medieval castle built as headquarters for the Pope's secretive Knights Templar.

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

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

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

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

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

The world's oldest bookshop still in operation.

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

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

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

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 hidden tunnel leads to an abandoned slate quarry that's now a secret swimming spot guarded by cliffs.

The painting on an aptly named street honors the 1980s slasher movie.

An impromptu shrine appeared shortly after beloved "Torchwood" character Ianto Jones was killed off the show.

This pedestrian walkway cuts through a cemetery and over several burial vaults.

Go deep down into the earth to experience the world of Welsh coal miners.