The Mausoleum of Lucius Munatius Plancus (22 BCE) is a cylindrical travertine monument at the top of Monte Orlando (168 m). It stands at 13.20m and has a diameter of 29.50 m.
The Sanctuary of SS. Trinità, mentioned as early as the 11th century and visited, among the others, by St. Francis and Saint Philip Neri. Its Chapel of the Crucifix is a curiosity: it has been built on a huge mass of rock that hangs like a wedge between two adjoining walls of rock. Legend tells how the rock was thus split at the moment of our Saviour's death.
From the sanctuary the Grotta del Turco can be visited: it is a grotto which ends directly in the sea and where the waves create atmospheric effects of light.
The Church of Annunziata (1320), was rebuilt at the beginning of the 17th century in Baroque style by Andrea Lazzari. It houses works by Luca Giordano, Sebastiano Conca and Giacinto Brandi, as well as the sarcophagus of Enrico Caracciolo, a notable Gothic work of art.
The most interesting sight is however the Golden Grotto, a Renaissance room where Pope Pius IX devised the dogma of Papal infallibility. The walls of the grotto are decorated with 19 panels by Giovan Filippo Criscuolo (1531) into carved and gilded frames with small pilasters. On the altarpiece is an Immacolata by Scipione Pulzone. 
The Church of San Giovanni a Mare was built by the hypate Giovanni IV in the 10th century, outside the old sea walls of the city. It is a rare example of fusion between the basilica form with the Byzantine one. The simple façade has a Gothic portal and a decorated dome, while the interior has a nave with two aisles. The inner pavement is slightly inclined to allow waters to flow away after sea floods. 
The Cathedral of Assunta was erected over a more ancient church, Santa Maria del Parco, and consecrated by Pope Paschal II in 1106: it had a nave with six aisles separated by columns with Gothic capitals. In 1778, however, two of the aisles were suppressed and the Gothic lines hidden. In the 13th century Moorish arches were added over the capitals. In 1663 the crypt was decorated in Baroque style. The interior houses a banner from the Battle of Lepanto, donated by Pope Pius V to Don John of Austria, who used it as his admiral's flag. The main sight of the church is however the marble Paschal candelabrum, standing 3.50 m tall, from the late 13th century: it is in Romanesque style, decorated with 48 reliefs in 4 vertical rows, telling the Stories of the Life of Jesus. There are also paintings by Giacinto Brandi and Giovanni Filippo Criscuolo. The cathedral contains the relics of St. Erasmus, transferred from Formiæ; the campanile (see picture below), in Norman style, dates from 1279. Standing at 57 meters, is considered the city's finest piece of art. The base has two marble lions, and the whole construction made large reuse of ancient Roman architectural elements. 
The large church of St. Francis, according to the legend constructed by the Saint himself in 1222, was in fact built by Frederick II, in very fine Gothic-Italian style, and contains paintings and sculpture by many of the most famous Neapolitan artists. 
The Medieval Quarter of Gaeta is itself of interest. It lies on the steep sides of Mount Orlando and has characteristic houses from the 11th-13th centuries. 
Gaeta is also the centre of the Regional Park of Riviera di Ulisse, which includes Monte Orlando, Gianola and the Scauri Mounts, and the two promontories of Torre Capovento and that of Tiberius' Villa at Sperlonga. In the picture below, the ruins of the emperor's Villa.
The Pinacoteca (picture gallery) offers remarkable local pictorial testimonies of the Early Middle Ages and late Gothic among which Giovanni Da Gaeta's frescos of the fifteenth century. Here is also conserved the precious "Stendardo della Battaglia di Lepanto" (The banner of Lepanto's battle) of 1571 attributed to Girolamo Siciolante. The picture gallery collects moreover some painting of the Renaissance and Baroque Ages of various painters (below, the Patrons of Gaeta, a work by Sebastiano Conca).
The Archeological Museum collects a section of finds that date their origin to the Roman period: vases, utensils and funerary sets found in Gaeta during excavations of public works or in the Gulf waters. A considerable collection of tombstones, capitals, columns and ceramics of the Middle Ages, coming from the ancient "Castrum" enriches the exposition. 
The Church of San Giovanni a Mare was built by the hypate Giovanni IV in the 10th century, outside the old sea walls of the city. It is a rare example of fusion between the basilica form with the Byzantine one. The simple façade has a Gothic portal and a decorated dome, while the interior has a nave with two aisles. The inner pavement is slightly inclined to allow waters to flow away after sea floods.
The Cathedral of Assunta was erected over a more ancient church, Santa Maria del Parco, and consecrated by Pope Paschal II in 1106: it had a nave with six aisles separated by columns with Gothic capitals. In 1778, however, two of the aisles were suppressed and the Gothic lines hidden. In the 13th century Moorish arches were added over the capitals. In 1663 the crypt was decorated in Baroque style. The interior houses a banner from the Battle of Lepanto, donated by Pope Pius V to Don John of Austria, who used it as his admiral's flag. The main sight of the church is however the marble Paschal candelabrum, standing 3.50 m tall, from the late 13th century: it is in Romanesque style, decorated with 48 reliefs in 4 vertical rows, telling the Stories of the Life of Jesus. There are also paintings by Giacinto Brandi and Giovanni Filippo Criscuolo. The cathedral contains the relics of St. Erasmus, transferred from Formiæ; the campanile (see picture below), in Norman style, dates from 1279. Standing at 57 meters, is considered the city's finest piece of art. The base has two marble lions, and the whole construction made large reuse of ancient Roman architectural elements.
The large church of St. Francis, according to the legend constructed by the Saint himself in 1222, was in fact built by Frederick II, in very fine Gothic-Italian style, and contains paintings and sculpture by many of the most famous Neapolitan artists.
The Medieval Quarter of Gaeta is itself of interest. It lies on the steep sides of Mount Orlando and has characteristic houses from the 11th-13th centuries.
Gaeta is also the centre of the Regional Park of Riviera di Ulisse, which includes Monte Orlando, Gianola and the Scauri Mounts, and the two promontories of Torre Capovento and that of Tiberius' Villa at Sperlonga. In the picture below, the ruins of the emperor's Villa.
The Pinacoteca (picture gallery) offers remarkable local pictorial testimonies of the Early Middle Ages and late Gothic among which Giovanni Da Gaeta's frescos of the fifteenth century. Here is also conserved the precious "Stendardo della Battaglia di Lepanto" (The banner of Lepanto's battle) of 1571 attributed to Girolamo Siciolante. The picture gallery collects moreover some painting of the Renaissance and Baroque Ages of various painters (below, the Patrons of Gaeta, a work by Sebastiano Conca).
The Archeological Museum collects a section of finds that date their origin to the Roman period: vases, utensils and funerary sets found in Gaeta during excavations of public works or in the Gulf waters. A considerable collection of tombstones, capitals, columns and ceramics of the Middle Ages, coming from the ancient "Castrum" enriches the exposition.