The first mosque in the world to receive electricity.

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.

A towering spire in the fortress of Kalemegdan honors the victorious armies of Serbia during their struggles against the Ottoman Empire.

This scale model of our solar system hid in plain sight for years before a physics team sought out all the planets.

An underground paleo-Christian burial site composed of the remains of several cemeteries and Basilicas.

A sulfuric hellscape in southern Italy.

Ancient snack bar of the Roman Empire re-opened.

Erotic art covers the walls of the largest ancient pleasure palace.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

This one-of-a-kind archeological site is home to strange prehistoric ruins, the original use of which is still a mystery.

A medieval replica of King Arthur's legendary table, the Round Table hanging in Winchester Castle was decorated by Henry VIII.

Famously misunderstood wonder of the ancient world

Tables of secondhand books fill the inner courtyard of this 17th-century stock exchange.

At just 51 feet and 10 inches long, it's the shortest street in England.

This preserved puppy was an adorable beacon of charity.

A replica of the steam engine that hauled Queen Victoria's Royal Train is on display at Windsor.

All unmarked mute swans on the Thames are owned by the Queen per a tradition that began in the 12th century.

These stark white cliffs were spat up by the sea and are slowly being retaken by it.

The second-largest gold nugget in existence, displayed in a Las Vegas casino conveniently named the Golden Nugget.

High on a hill overlooking Los Angeles lives a world famous, high power conical Tesla Coil.

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

A marvel of Byzantine engineering under the streets of Istanbul.

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