Trajan's Markets, Rome

Completed around AD 113 as part of Emperor Trajan's grand forum, Trajan's Markets are often called the world's first shopping mall—a monumental multi-level complex of some 150 rooms and shops (tabernae) built into the flank of the Quirinal Hill. Designed by the brilliant architect Apollodorus of Damascus, its bold use of brick-faced concrete, barrel vaults, and a great vaulted hall was centuries ahead of its time. The shops likely sold everything from wine and oil to spices and silk, while offices administered the grain dole that fed Rome's poor. Rising six storeys up the hillside, the semicircular structure survives remarkably intact. In later centuries it was fortified with a medieval tower; today it houses the Museum of the Imperial Forums.