This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

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

An ancient Roman temple first dedicated to an emperor's wife is now a church.

A fairy tale castle in modern Rome.

Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

An 18th-century post box used to alert the church of sick and ailing foreign pilgrims.

A sculpture serving as an homage to Pope John Paul II.

The mystic whose incorrupt corpse still attracts the faithful.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

This is the oldest Roman-made bridge in the city still existing in its original state.

In Rome’s Jewish ghetto, a 200-year-old bakery still makes the neighborhood’s historic sweets.

This gallery commissioned by Cardinal Spada is known for its magnificent optical illusion.

This hidden alley near the location of Rome's first theater was the site of a curious miracle.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

Also known as the Square Colosseum, this building is a prime example of fascist-era rationalist architecture.

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

Ancient ruins hidden underneath a modern luxury hotel.

An ancient Egyptian obelisk is now used to commemorate fallen Italian soldiers.

A memorial to the victims of Argentina's "Dirty War."

The final resting place of the liberator of Argentina is guarded around the clock by two soldiers.

A mysterious architectural gem in one of the most elegant areas of Buenos Aires.

Museum housed in underground tunnels that date back to Buenos Aires's earliest settlements.

The narrowest house in Buenos Aires is less than 10 feet wide.

A tower devoted to — and modeled after — the Divine Comedy.