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

A statue commemorating a beloved stray dog who was adopted by the entire neighborhood where he lived.

A pair of gigantic baby heads greet passengers at Atocha Station.

This fountain was designed to honor the man who helped bring water to Barcelona.

On the wall of this medieval square, a symbol of the Spanish Inquisition.

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

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

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

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

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

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

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

This colorful statue welcomes visitors to a Barcelona park.

An early 20th-century bullring converted into a modern shopping center.

A bookstore dedicated to the intersection of comedy and art.

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

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

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.

This historic recreationist school churns out warriors that may very well have had a fighting chance in Rome's pits of the day.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

Nicolas Schöffer's massive interactive sculpture was assembled in 1961 and brought back online in 2016.

This abandoned Belgian fortress is purposefully being left to nature.

A secret hatch containing two parchments was discovered in this statue over 40 years after its installation.