Ponte Sistowas the first bridge to be built across the river Tiber since the days of antiquity.
In the Holy Year of 1450, there was a disaster on Ponte Sant' Angelowhen in the region of 200 pilgrims were crushed to death in a stampede. Ponte Sant' Angelo was the only bridge between the centro storico to St Peter's Basilica. Pope Sixtus IV (r. 1471-84), fearing a repeat of such a disaster during the Holy Year of 1475, ordered a new bridge to be built further upstream. Its designer is thought to have been the Florentine architect Baccio Pontelli (1450-92), who used the foundations of the ancient Pons Antoninus, which was erected by Emperor Marcus Aurelius (r. 161-80).
On the parapet of the east bridgehead are copies of two marble slabs, which bear a Latin inscription composed by the humanist Bartolomeo Platina (1421-81) in honour of Sixtus IV.
XYSTVS IIII PONT MAX / AD VTILITATEM PRO PEREGRINAEQVE MVLTI / TVDINIS AD IVBILEVM VENTVRAE PONTEM / HVNC QVEM MERITO RVPTVM VOCABANT A FVN / DAMENTIS MAGNA CVRA ET IMPENSA RESTI / TVIT XYSTVMQVE SVO DE NOMINE APPELLARI / VOLVIT. (For the convenience of the people of Rome, and of the multitude of visitors bound for the Jubilee, Sixtus the Fourth, Pontifex Maximus, with great care and at great expense, rebuilt from its foundations this bridge, which in former times they justly called broken, and willed that it should be called Sixtus after his own name.)
MCCCCLXXV / QVI TRANSIS XYSTI QVARTI BENEFICIO / DEVM ROGA VT PONTEFICEM OPTIMVM MAXI / MVM DIV NOBIS SALVET AC SOSPITET BENE / VALE QVISQVIS ES VBI HAEC PRECATVS / FVERIS. (1475. You who cross by the kindness of Sixtus the Fourth, pray to God that he may long keep and preserve for us our supreme and excellent pontiff. Farewell, whoever you may be, once you have offered this prayer.)