Construction crews building a new section of Milan’s subway line have uncovered an unexpected window into the city’s ancient past. While lowering deep concrete tunnels beneath the modern streets, archaeologists uncovered the remains of a Roman horreum—a large warehouse used in antiquity for storing grain and other essential goods. Facilities like these served a key function in the economy of the Roman Empire, securing and distributing food supplies and commodities to urban centers. The discovery in Milan, ancient Mediolanum, offers new evidence of how this northern Italian hub was connected to broader trade networks, including routes across the fertile Po Valley that linked communities and markets throughout the empire.