Above is one of the fountains alongside Porta San Niccolò, a city gate first constructed in 1324. Other gates in the city were lowered during the sixteenth century, but this was one was left at its original height.
This is from what was the inside of the gate, with Piazzale Michelangelo visible on the right-hand side of the photo. There were debates about demolishing it in the nineteenth century, with the nearby city walls being taken down, but the gate was saved because of the excellent views of the city from its top. Visitors can still climb to the top of the tower, but only during the summer months.
And this is what the gate looked from the outside, quite a formidable structure.