A haven for book enthusiasts across the street from Retiro Park.

One of the best examples of the modernist movement in Madrid.

This unassuming bookstore in the heart of Madrid is one of the oldest in Spain.

This enigmatic artifact is a rare depiction of an ancient Iberian noblewoman.

An iconic and controversial ancient Iberian funerary urn with a hauntingly penetrating gaze.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

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

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

A lush indoor jungle fills this bustling Madrid transportation hub.

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.

This small park features a monumental fountain wall, providing a great photo opportunity in the middle of Houston.

The largest underground pedestrian tunnel system in the U.S. mostly caters to the people working in the offices above, but provides a great, air-conditioned way to traverse the city.

A taste of Middle Earth, in the middle of the Bayou City.

This home designed for chocolate magnate Antoni Amatller is an exquisite treasure-box of Catalan Modernism.

One of Antoni Gaudí’s earliest buildings, built between 1886 and 1890 for the industrialist Eusebi Güell.

Occupied for six centuries by Franciscan Order nuns, this monastery is an amazing ode to Catalán Gothic architecture.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

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

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

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

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

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