 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.The three-arched Fontana dell'Acqua Felice (designed by Domenico Fontana, 1587) marked the entry of the new water source into Rome, with the conventional "mostra" or showy terminus