Aurelian Walls

Between 271 and 275, six centuries after the construction of the Servian walls, Rome was once again in danger, threatened by populations from northern Europe. After the third invasion by the Alemanni, the emperor Aurelian decided to build new fortifications to replace the walls of the Republic, which had been made obsolete by the expansion of the city.

The route, which ran inside imperial properties to limit expropriations, followed the slopes of the land, took advantage of ditches and elevated areas, included aqueducts and all structures that could be used for defensive purposes. With a length of about 19 km, the route opened up at the pre-existing road axes with seventeen main gates and some posterns (ARDEATINE).

Aurelian’s walls were built in opus latericium with mostly reclaimed materials and rarely reached a height of more than 8 metres, with an average thickness of 3.50 metres. Along the top an uncovered patrol path was sheltered by a crenelated parapet. Massive square towers, equipped with a covered chamber used for war machines, marked the route every 30 metres.

Between 401 and 403, due to the danger from fresh invasions, Emperor Honorius initiated a general rebuilding of the walls. The entire structure was reinforced, and the walkways and towers were raised by one storey. The former patrol path was transformed into a vaulted covered gallery, above which another uncovered walkway was created and protected by battlements, with a total height of about 12 metres. A second manoeuvring chamber for the war machines was built in the towers, covered by a four-sided roof.

At this stage, the walls took on their present appearance, but the great transformation did not prevent Alaric from sacking Rome (410) or the Vandals from invading later (455). Belisarius, the Byzantine general of Justinian’s time (482-565) had the walls restored several times, but could not prevent the invasion of Totila’s Ostrogoths.

In the Middle Ages, as the city shrank in size, and the walls also contained large uninhabited areas, they nevertheless retained a strong visual value and, above all, a legal value as a customs barrier. Their maintenance was entrusted to the popes. From the 10th century, with the decline of the two main powers, the Empire and the Church, the struggles for supremacy between powerful families were all within the walls, which gradually lost importance. Some sections were abandoned or used for different purposes. It was not until the second half of the 12th century that the city senate took over the care of the walls and in 1157 carried out a major restoration, as confirmed by an inscription in the Porta Metronia wall.

The gates also took their names from the nearby basilicas or catacombs: Porta Appia became Porta San Sebastiano, today the seat of the Museo delle Mura; Porta Asinaria became Porta San Giovanni; Porta Aurelia took the name of Porta San Pancrazio; Porta Flaminia was first called Porta San Valentino and then Porta del Popolo; Porta Labicana became Porta Maggiore; Porta Ostiensis is remembered as Porta San Paolo; Porta Tiburtina became Porta San Lorenzo.

From the 15th century the restoration of the walls was again commissioned by the popes, who affixed coats of arms and inscriptions to them. The symbol of papal power first replaced the authority of the Roman Senate during the Jubilee of 1450, when the coat of arms consisting of the two crossed keys of Pope Nicholas V appeared on the walls.

Following the Sack of the Landsknechts (1527), Pope Paul III entrusted Antonio da Sangallo the Younger and Michelangelo with the task of reinforcing the city’s defences. Of the eighteen bastions in their project, only the Ardeatine Bastion (1537-42) and the Colonnella Bastion were built.

Two new gates were also built during this period, Porta del Popolo and Porta San Giovanni, in place of the previous Porta Flaminia and Porta Asinaria.

The most significant 19th-century works are attributable to Giuseppe Valadier and Virginio Vespignani, who, during the pontificate of Pope Pius IX (1846-1878), undertook a major restoration programme. It was Pope Pius IX himself who in 1847 officially entrusted the care of the walls to the Municipality of Rome and in 1870 carried out the final transformations of the circuit to defend the city from the Army of the Kingdom of Italy, which nevertheless proved victorious.

Following this, Rome was proclaimed capital of the Kingdom and the Walls, having lost their function, followed the needs of urban expansion, in which sections were removed or mutilated. Nevertheless, they were destined to become the city’s most impressive and representative monument.