A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

This medieval synagogue survived the Inquisition as a hospital and church.

The world's largest wooden structure.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

The final resting place of the great navigator, or maybe his brother.

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

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

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

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

Building owners can take out tiles for free at this repository for historic building materials.

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

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

The corpse bride of Portugal.

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

A fortress off the West coast of Portugal that dates back to 1502.

Get in line for Lisbon’s most famous sandwich.

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

The best place in the world to buy tinned fish.

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

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

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.

Street artists transformed this abandoned industrial neighborhood into one of Europe's largest graffiti exhibitions.