Perhaps the most spectacular grotto along the Algarve coastline.

One of the smallest bookstores on the planet.

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

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

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

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

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

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

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

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

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

A small Portuguese cottage formed between boulders in the countryside.

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.

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

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

This charming candle shop has been in business since 1789.

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

The stunning interior of this Gothic church is covered in ornate gold details.

A submerged village appears when dam levels drop.

The world's oldest bookshop still in operation.

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

Double spiral staircases are not unheard of, but they are very rare.

Built to test magnetically levitated elevators, the tower also boasts Germany's highest visitor platform.