 From the source, which Sixtus purchased, there was only a very small fall, and the work required an underground conduit as well as an aqueduct carried on arches.The work was completed within eighteen months, at the same time that Sixtus was engaged in laying out the street plan that would provide the arteries of modern Rome.By October 1586, water was running at his Villa Montalto, and by 1589 it was filling no less than twenty-seven public fountains.