Rome, ancient Tiber bridge Pons Neronianus remains between modern Ponte Vittorio Emanuele II in front and modern Ponte Principe Amedeo Savoia Aosta behind.

Ponte Vittorio Emanuele II is a bridge in Rome constructed to designs of 1886 by the architect Ennio De Rossi. Construction was delayed, and it was not inaugurated until 1911. The bridge across the Tiber connects the historic centre of Rome (Corso Vittorio Emanuele, whose axis the bridge extends, and piazza Paoli at the bridgehead) with the rione Borgo and the Vatican City, close to the few remains of the Roman Pons Neronianus. The bridge commemorating Vittorio Emanuele II of Italy is carried in three arches spanning a distance of 108 metres. It is decorated at the ends with high socles carrying colossal bronze winged Victories and over each of the piers with massive allegorical travertine sculptural groups.

Ponte Principe Amedeo Savoia Aosta, also known as Ponte Principe or Ponte PASA after its acronym, is a bridge that links Lungotevere dei Sangallo to Piazza Della Rovere in Rome (Italy), in the Rioni Ponte, Trastevere and Borgo.

The Pons Neronianus or Bridge of Nero was an ancient bridge in Rome built during the reign of the emperors Caligula or Nero to connect the western part of the Campus Martius with the Campus Vaticanus ("Vatican Fields"), where the Imperial Family owned land along the Via Cornelia.
There is no direct evidence that Nero actually built the bridge named after him. It may well have been named the 'Bridge of Nero' because the area on the right bank of the Tiber beyond the bridgehead was still named the "Plain(s) of Nero" well into the Medieval period, so that the inhabitants of Rome at that time, not knowing the origins of the ruined bridge, named it after the region rather than after Nero himself. Whatever its origins, the bridge gave Nero easier access to the Gardens of Agrippina, his mother Agrippina the Younger's riverside gardens and portico which were located on the right bank just downstream from the bridge.
The Emperor Caligula built a circus on the right bank of the Tiber. The historian Tacitus says it was in this circus, renamed the Circus of Nero, that the Emperor Nero executed the Christians who were accused of causing the Great Fire of Rome of 64 AD, in order to entertain the people of Rome after that fire. It is believed that Nero replaced the timber bridge of the Via Triumphalis with the stone bridge named after him, the Pons Neronianus or 'Triumphalis' because the Via Triumphalis, the Triumphal Way, passed over it. The people of Rome most likely crossed the Pons Neronianus to get to the Circus of Nero.
Starting with Titus, the victorious Emperors celebrating their Triumphs entered Rome marching across the Pons Neronianus along the Via Triumphalis. It is probable that the capacity of the Pons Neronianus could not cope with the day to day traffic in Rome because within a century of its completion the Emperor Hadrian built the Pons Aelius less than two hundred metres upstream. Nero's bridge was also called Pons Vaticanus (meaning "Vatican Bridge" in Latin), because it connected the Ager Vaticanus to the left bank. The bridge may well have been in ruins in the fourth century. Certainly, by the Middle Ages the bridge was called Pons ruptus ("Broken Bridge"), because it was broken. In the fifteenth century Pope Julius II planned to restore it. The Pons Neronianus crossed the river immediately below the modern Ponte Vittorio Emanuele II, but at a slightly different angle; little of the ancient structure survives today. When the Tiber is at low water level it is possible to see the foundation of one of the four piers that once supported the Pons Neronianus. However, in the nineteenth century all the piers were still visible above water. These were removed to allow boats to pass safely up the Tiber.

more on https://en.wikipedia.org/wiki/Ponte_Vittorio_Emanuele_II , https://en.wikipedia.org/wiki/Ponte_Principe_Amedeo_Savoia_Aosta , https://en.wikipedia.org/wiki/Pons_Neronianus