A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

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

Inside this building is another country within Rome, a sovereign entity without a physical territory.

Architectural monsters are devouring this palace's every door and window.

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

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

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

A rare example of a medieval house in Rome adorned with a melancholic inscription.

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 "Great Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

Rome’s legendary peephole vista is also a former Crusader stronghold.

Once the home of a renowned slaughterhouse, formerly working-class Testaccio is still the place to go for Roman offal dishes.

The final resting place of the poets Shelley and Keats.

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

A small cell adjacent to this church was once the bedroom for a renowned saint.

A Swiss board game museum housed inside a picture-perfect castle.

The world's tallest palm trees look like the whimsical kind of plant you'd find in a Dr. Seuss story.

This unofficial museum details the rise and fall of Colombia's most notorious narcotrafficker, Pablo Escobar.

An ancient city hidden in the heart of the Sierra Nevada mountains.

Outdoor escalators and art have helped change what was once a notoriously dangerous part of Medellín.

In the heart of Medellín, an artsy urban complex sets the stage for demonstrations and protests.

Two identical statues by Fernando Botero, one blown to pieces in a terrorist bombing, the other donated as a gift for peace.