This plaza is home to a number of works, including Montpellier‘s own Arc de Triomphe.

The world's largest reflecting pool is just two centimeters deep.

The experimental test tracks of a retro-futuristic monorail still stand in the French countryside.

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

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

Ancient ruins hidden underneath a modern luxury hotel.

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

This hydrochronometer was invented by a Dominican monk and is a prime feature in this garden.

A forgotten "city of water" underneath the famous Trevi district.

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

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

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

This basilica is dedicated to two saints, one of which is known more for his famous quote.

This spectacular dome managed to survive after being bombed in World War II, in an event known as the "Miracle of Mosta."

The floor of this spectacular Baroque sanctuary is covered in memento mori.

Stone Age solar temple is aligned with the sun on each equinox and solstice.

This unique building in the main square stands out among the city's typically Baroque architecture.

Burial grounds for more than 1,000 bodies deep under the modern town of Rabat.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

These temples are among the oldest free-standing stone buildings in the world.

This prison on the Maltese island of Gozo is almost 500 years old, and they have the graffiti to prove it.

The fishing boats that moor in this small lagoon enter and leave through a tunnel to the sea.

Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.

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