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

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.

The tallest mountain in mainland Netherlands isn't actually very tall.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

A Nesting Doll of Churches.

This ancient market is often referred to as the oldest shopping mall in the world.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

A large replica of a monumental Roman inscription is located on the side of this museum.

This small church was constructed over the ruins of three temples dating to the Roman Republic.

The remains of this 2nd-century Roman temple are incorporated into a modern building.

An 18th century fountain and two columns are all that remains of Rome's forgotten river harbor.

A monumental fountain in Rome features a large statue of Moses that has been criticized for centuries.

This one-of-a-kind Roman arch is not actually dedicated to the god Janus.

Romans decided this 16th-century "talking statue" was so ugly, they named it after a primate.

This small, ancient Roman temple was once a church dedicated to the patron saint of penitents.

This curious, round temple is the oldest still-standing marble building in Rome.

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

This large, circular tomb is the final resting place of the first emperor of Rome.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

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

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.