The only surviving choragic monument is a trophy awarded in 334 BC for the winning dramatic chorus.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

The red letters in the literary pavement leading to the library form a mysterious code.

Long tunnels run under the ancient chariot racing circuit to the tower.

Originally built for London’s cab drivers, this bright green hut now serves anyone a hot drink or meal.

The remains of the left arm of the levitating philosopher-saint are kept in a 13th-century Neapolitan basilica.

This 6th-century church has the largest and best-preserved collection of Byzantine mosaics outside Constantinople.

Legend has it this fountain built to symbolize the Pope’s power hides a strange secret concerning Neptune's manliness.

Why a column on the entrance is inscribed with a verse from the Quran is one of Sicily's many mysteries.

The burial place of an obscure North African saint was turned into a macabre body preservation factory for the 17th-century Neapolitan elite.

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

Over 100 towers were built in Bologna during the Middle Ages, but only 22 survive.

The "dragon babies" of southeastern Europe.

A whimsical bridge adorned with decorative dragons.

One of the largest caves in the world open to the public.

This massive subterranean fissure is known as the "underground Grand Canyon."

A miniature train-ride through Slovenia's largest cave system.

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

This 15th-century island fortress later served as home to the executioners no one wanted to live near.

This strategic isle was once swapped between empires and almost entirely destroyed in a bomb explosion.

This bustling Italian plaza is built on the ruins of an ancient Roman amphitheater.

The last four extravagant street signs of London's historic banking street.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.