Roman engineering [overhead power line history]

A modern engineer visiting Rome, as the author did recently, cannot fail to be impressed by the work of the Roman engineers of 2000 years ago. However much manual labor was available in the capital of the empire, the planning and construction of the Colosseum and the Pantheon were magnificent engineering achievements. Large numbers of stone blocks weighing up to 9 t were cut accurately to size and lifted as much as 10 m into the air and placed accurately in position. The roof of the Pantheon alone, a dome more than 40 m across, would be a noteworthy feat today. Aqueducts on brick or stone arches carried water more than 20 km into the city from sources in the Appenine hills. One came from Tivoli, an area noted for its natural beauty, which since classical times has provided a country retreat for wealthy Romans. One hundred ten years ago, on 4 July 1892, Roman engineering reached another achievement. On that day, an overhead transmission line first brought electricity at 5000 V into the city from a new hydroelectric station at Tivoli. Today one can stand in the power station grounds and see an ancient aqueduct, which looks as if it will still be there in another 2000 years. Will the power station last that long?.