A perfectly circular lake is formed by the crater of an ancient underwater volcano.

This star-shaped military outpost is now simply trying to protect itself from neglect.

"Portugal's Stonehenge" is made up of nut-like stones aligned with the heavens.

Ancient catacombs form the foundation for this Rococo orgy of a church.

Elaborate tile work in this railway station tells the story of Portugal.

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

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

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.

This abandoned five-star hotel is now a five-star urban exploration destination.

A small Portuguese cottage formed between boulders in the countryside.

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.

A garden in Lisbon filled with giant porcelain creatures.

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

This charming candle shop has been in business since 1789.

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

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

This restored Portuguese cafe may well be the most beautiful place in the world to grab a Big Mac.

Pagan monument converted to Christianity with the population.

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

Catering to broken dolls for almost 200 years, this repair shop is now a charnel house of doll parts.

A cluster of granite granaries perched on stilts.

An early Portuguese serial killer's head is alarmingly well preserved in a jar at the University of Lisbon.