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

Giant eggs, walls of bread, and nightmare surreality mark the largest collection of works by Salvador Dalí.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

A lush indoor jungle fills this bustling Madrid transportation hub.

Commonly acknowledged as the only public monument to the Devil himself.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

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

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

Bacteria and algae give the salty water its bubblegum hue.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

An ancient Egyptian temple in the middle of Madrid, Spain.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Mountain where Jesus was first tempted by the Devil.

Gaze upon chocolate sculptures depicting everything from chariot races to Gaudí's famous church at this shrine to sweets.

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

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

The Cathedral of Salamanca has a number of unusual carvings but none so surprising as a modern astronaut.