In the 14th century, the Savelli family built their castle on the Aventine Hill, making the hill an impregnable fortress. The massive medieval walls now enclose Parco Savello (also known as the Garden of Oranges), a small rectangular garden that is very popular because from the belvedere overlooking the river, there is a splendid view of Rome that extends from the bend of the Tiber to St. Peter's Basilica. The trees that give it its name were planted in memory of St. Dominic, who founded his convent here.

The park was built in 1932 according to a design by the architect Raffaele De Vico, who enhanced the space enclosed within the ancient walls. In the enclosing wall, on the side opposite the lateral wall and the apse of S. Sabina, the traces of the towers and the drawbridge of the castle are clearly recognizable.

The walls bear the signs of a subsequent arrangement of the area, carried out at the end of the 16th century by the architect Fontana on commission of Sixtus V. Following the great leveling work, the foundations of the walls were exposed on one side, while on the other the level of the entrance gate rose by over three meters from the new street level, as can be seen by observing the wall from the outside, in the last stretch of the clivo di Rocca Savella.

Apart from the fortified wall, of the 13th-century castle and its subsequent expansions only some granaries and underground warehouses remain, while the building was almost completely demolished in 1613.

Leaving the Garden of Oranges, turn right and reach Piazza dei Cavalieri di Malta (designed by the famous engraver Giovan Battista Piranesi in 1765). From the keyhole of the gate that leads to the Villa dei Cavalieri, you can see the dome of St. Peter's, framed by the hedges of the gardens.