The grand Fontanone di Ponte Sisto stands in Piazza Trilussa, facing the south end of the Ponte Sisto. It was designed by the Dutch architect Jan van Santen (1550-1621), better known as Giovanni Vasanzio, at the behest of Pope Paul V (r. 1605-21).
However, the fountain, which was also known as the Fontanone dei Cento Preti (Grand Fountain of a Hundred Priests), originally stood on the other side of the river, where it was part of the facade of the Collegio Ecclesiastico.
At the end of the 19th century the college became a casualty of the construction of the Lungotevere, the twin roadways that crown the embankments on either side of the river. Mercifully, the fountain survived. It was dismantled and erected on its present site in 1898, as the lower plaque proclaims.