The Ponte Sisto is one of the bridges which link the two banks of the river Tiber in Rome. It was built between 1473 and 1479 by Pope Sixtus IV who (like all Popes) appropriately held the title Pontifiex Maximus. This title was held by the Roman Emperors before the Popes and by pagan Roman priests before them. I say appropriately because the title is thought to mean ‘Bridge Builder General’. As such it signified that the chief priest of Rome was responsible for building bridges across the sacred river Tiber but also that he built bridges between humans and the Gods (an appropriate reason for it being transferred to the Pope).
The Ponte Sisto represents the cutting edge of 15th-Century engineering and has a hole (oculus) in the middle for water to flow through in the event of flooding, taking pressure off the structure and making it less likely to collapse.