The Ancient World's Longest Underground Aqueduct Roman engineers chipped an aqueduct through more than 100 kilometers of stone to connect water to cities in the ancient province of Syria. The monumental effort took more than a century, says the German researcher who discovered it. When the Romans weren't busy conquering their enemies, they loved to waste massive quantities of water, which gurgled and bubbled throughout their cities. The engineers of the empire invented standardized lead pipes, aqueducts as high as fortresses, and water mains with 15 bars (217 pounds per square inch) of pressure. PHOTO GALLERY: ROME'S LONGEST PIPE In...