- Cattedrale di S. Erasmo: the cathedral was built on a previous church dedicated to S. Maria del Parco in VII century, consecrated by Pope Pasquale II in 1106. Inside there are many works of art, such as the Neoclassical baptismal font (the base is attributed to Canova), the wood choir of 1500, the Easter candle of XIII century decorated with episodes taken from the life of Jesus and S. Erasmo. In the rich crypt of 1600 there are the bodies of Erasmo and Marciano (Patrons), Innocenzo, Secondino, Porbo, Casto and Europa. The bell tower is 57 m tall. It is in Arabian – Norman style and was built in 1279, with windows with two lights, small arches, majolica and small towers. In the base there are Roman fragments. At the entrance there is a basso-relievo portraying a whale of the sea eating Jonah.
- Museo Diocesano: the museum contains sculptures and fragments of the early cathedral and of other churches of the territory, paintings by Giovanni da Gaeta, Quentin Metsys, Luis de Morales, S. Pulzone and F. Santafede.
- Museo De Vio: this archaeological museum contains paintings and frescoes coming from churches of the town and of the territory.
- Tempio di S. Francesco: Saint Francis built this temple in 1222
in the place where he stayed when he evangelized the inhabitants
of Gaeta. The current neo-Gothic structure was carried out thanks
to the contributions of two monarchs: Charles II of Anjou and Ferdinand
II Bourbon. On the façade, there are their statues and a
statue portraying Saint Francis. There is also a beautiful statue
portraying Faith supporting the Cross.
Chiesa di S. Giovanni a Mare: this church was built in X century by Duke of Gaeta Giovanni IV. The dome is in Arabian style and the floor is sloping to let the water flow. In fact the church was built near the sea and sometimes it was invaded by waters.
- Chiesa di S. Lucia: the church dedicated to Saint Lucy is maybe the most ancient in Gaeta, and it was built in VII century. There are three naves separated by rows formed by four columns. Inside there are works of art by Giova di Gaeta.
- Chiesa dell’Annunziata: the church was built in 1321 by the University of Gaeta in Gothic style with a nave. In 1355 a hospital was annexed to it: it had to give hospitality to poor and old people, to abandoned children. Inside, on one of the sides there is a corridor with the sarcophagus of E. Caracciolo, a late-gothic masterpiece. After that, there is a chapel called Grotta d’Oro, in which several popes prayed (among them John Paul II). The chapel has a barrel-vault with golden wood decoration. In this chapel, Pope Pius IX meditated about the dogma of Immaculate Conception. The church contains 19 paintings by Criscuolo and a painting by Pulzone. The church contains also precious codes with sacred music, hand-copied by monks. The miniatures decorating the manuscripts are beautiful. There is also a polypthyc by Andrea da Salerno.
- Chiesa di S. Maria di Porto Salvo: this church was built in XV century.
- Chiesa della Sorresca: built in XVI century.
- Chiesa di S. Caterina d’Alessandria: built in IX century.
- Chiesa di S. Domenico: built in XV century.
- Santuario della SS. Trinità: this sanctuary was built in XI century by Benedictine friars. It is situated in a crack in the rock. According to a legend, this crack opened when Christ died on the cross. In this sanctuary many Popes, saints and monarchs prayed. A legend tells that S. Filippo Neri lived in this place: now there is a rock called “bed of S. Filippo Neri”. Along the staircases leading underground, in the mountain, there is the so-called “Hand of the Turk”. It is a rock with the shape of a hand: according to a legend, this rock formed when a Turkish mariner sat on it. The rock became very soft and the hand was formed. A charming chapel dedicated to the Crucifix is on the precipice.
- Chiesa Santuario della Madonna della Catena: according to tradition, this church was built in the place where Our Lady with the Holy Child appeared. She held a chain, symbol of sins.
- Mausoleo di Lucio Munazio Planco: the monument was dedicated to Lucio Munazio Planco, a Roman consul in 22 b.C. The shape is cylindrical and it is decorated with war symbols. From the courtyard, visitors can admire a wonderful panorama.
- Mausoleo di Lucio Atratino: a monument dedicated to a Roman general, in La Catena area.
- Castello Angioino-Aragonese: the castle is the symbol of the town and it is very charming. The period in which it was built is not clear. Maybe it was built in VI century a.C. during Goth wars or in VII century a.C., during Longobard attacks. It surely existed during Svevian period when Frederick II stayed there several times. The castle is called Angevin – Aragon because it is made of two linked buildings built in different ages: the lower one was built during Angevin period. Charles V built the upper one during Aragon period. In the dome of the highest tower, there is a beautiful chapel, Cappella Reale, built by king Ferdinand Bourbon in 1849.