One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

A 16th-century Andalusian palace.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

Bacteria and algae give the salty water its bubblegum hue.

An architect transformed this abandoned cement factory into his castle-like workshop.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

The palace window through which Protestant nobles flung two Catholic regents, thus sparking the Thirty Years' War.

A deep mark on the remains of a Roman temple, believed to be left by a legendary warrior.

A small cell adjacent to this church was once the bedroom for a renowned saint.

An 18th-century post box used to alert the church of sick and ailing foreign pilgrims.

A statue representing a lost Roman profession that was vandalized for centuries.

Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

Also known as the Square Colosseum, this building is a prime example of fascist-era rationalist architecture.

Remnants of a 4th-century church with vivid medieval frescoes and ancient sarcophagi hide beneath this old basilica.

A wunderkammer of curious objects and intriguing art nestled within a hub of ancient Roman sites.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

Ancient ruins hidden underneath a modern luxury hotel.

One of the most important yet well-hidden museums dedicated to the history of medicine.

Roman-era ships unearthed...