Ponte Sisto

Commissioned by Pope Sixtus IV (hence the name) and built between 1473 and 1479 on the foundations of a ruined Roman bridge — making it the first new bridge in Rome since antiquity. It was funded by a tax on prostitutes in the Holy Year of 1475, ostensibly for Jubilee pilgrims arriving from south of the river. Pedestrianised today, it's the prettiest crossing into Trastevere on foot, and its central oculus (the round opening above the central arch) was designed to let floodwater through.