Largest cave system in Africa.

The tallest residential building in Africa is an unsettling Brutalist monolith.

Formerly known as the Malay Quarter, Bo Kaap is a colorfully-painted suburb located in the “Mother City” of South Africa.

Raging waters have created a strange geological site that looks like something off of a progressive rock album cover.

The final resting place of the poets Shelley and Keats.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

The yawning maw of this pagan visage is said to bite off the hands of liars.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

The first botanical garden, a feather in the cap of the Grand Duke of Tuscany.

The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.

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.

This ancient Roman prison is decorated with an upside-down cross not as blasphemy but as saintly tribute.

Jesus' footprints and the first catacombs in the world.

2300-year-old Roman road connecting the empire.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

Skulls from the plague of 1656 and World War II bombings are united by a cult dedicated to caring for the ancient dead.