Sessa Aurunca is a town of Campania, Italy, in the province of Caserta. It located on the south west slope of the extinct volcano of Roccamonfina.
It is situated on the site of the ancient Suessa Aurunca, near the river Garigliano. The hill on which Sessa lies is a mass of volcanic tuff.
The ancient chief town of the Aurunci, is believed to have lain over 600 m above the level of the sea, on the narrow south-western edge of the extinct crater of Roccamonfina. Here some remains of Cyclopean masonry exist; but the area enclosed, about 10 m by 50, is too small for anything but a detached fort. It dates more probably from a time prior to Roman supremacy.
In 337 BC the town was abandoned under the pressure of the Sidicini, in favour of the site of the modern Sessa. The new town kept the old name until 313, when a Latin colony under the name Suessa Aurunca was founded here. It was among the towns that had the right of coinage, and it manufactured carts, baskets and others. Cicero of it as a place of some importance. The triumviri settled some of their veterans here, whence it appears as Colonia Julia Felix Classica Suessa.
From inscriptions it appears that Matidia the younger, sister-in-law of Hadrian, had property in the district. It was not on a highroad, but on a branch between the Via Appia at Minturnae and the Via Latina crater mentioned.

The town contains many ancient remains, notably the ruins of an ancient bridge in brickwork of twenty-one arches, of substructures in opus reticulatum under the church of S. Benedetto, of a building in opus quadratum, supposed to have been a public portico, under the monastery of S. Giovanni, and of an amphitheatre.
The Romanesque cathedral is a medieval basilica with a vaulted portico and a nave and two aisles begun in 1103, a mosaic pavement in the Cosmatesque style, a good ambo resting on columns and decorated with mosaics showing traces of Moorish influence, a Paschal candelabrum, and an organ gallery of similar style. The portal has curious sculptures with scenes from the life of Saint Peter and Saint Paul. In the principal streets are memorial stones with inscriptions in honour of Charles V, surmounted by an old crucifix with a mosaic cross.

The hills of Sessa are celebrated for their wine.