The Walkway of the Aurelian Walls in Via Carlo Felice

Erected for the city's defence by Emperor Aurelian between 271 and 275 A.D., the city walls initially extended for about 18 kilometres, of which just over 12 are preserved today.

In particular, the stretch of walls between Porta Asinaria and the Amphitheater Castrense, flanked by today's Viale Carlo Felice, is one of the most imposing of the fortification. It consists of two galleries with superimposed arches due to the need to cross a small valley crossed by a stream, known in modern times as the "Marrana di San Giovanni", located between the line of the walls and Villa Wolkonsky, today the residence of the British Ambassador to Italy.

Pope Sixtus V (1585-1590) was the first to intervene in the arrangement of the wall belt by filling the valley and creating the straight line connecting the Basilica of Santa Croce in Gerusalemme and the Basilica of St. John Lateran. This backfilling was later completed on the occasion of the Jubilee of 1775 by Pope Benedict XIV (1740-1758), who made a direct connection between the Basilica of Santa Croce in Gerusalemme and that of St. John Lateran by realising a tree-lined avenue.