This massive blockhead sculpture hides an entire library.

Single runway interrupted by a busy road that cuts across its middle.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

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

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

Giant topiary dog once played a role in a terrorist bomb plot.

Holy Grotto of Montserrat Monastery holds one of Europe's mysterious black Madonnas.

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

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.

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

Construction of Barcelona’s iconic (but controversial) church was finally completed in 2026—a century after the death of its architect.

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.

Mosaics, storks, and brothels—this ancient city has it all.

The other side is actually green.

Traditional 11th-century outdoor tannery.

Thousands of narrow alleyways in an ancient medieval city make up what's believed to be the world's largest car-free urban zone.

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

A marvel of Byzantine engineering under the streets of Istanbul.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

Ancient serpentine sacrifice holder that has stood the test of time.

These Egyptian statues have survived for 3,400 years and were an acoustic wonder of the ancient world.

One of its engravings is believed to be among the first representations of medical and surgical instruments.