The origins of the Santa Maria Assunta church are uncertain. Its oldest part is the crypt, built in the 6th century on pre-existing Roman remains. The current church, however, dates back to the 11th century, built by the Norman king Roberto il Guiscardo and consecrated by Bishop Alfano I of Salerno in 1079. The Romanesque construction underwent significant restoration work in the Baroque style during the 18th century (between 1709 and 1716), mainly affecting the interiors.
The facade has a hipped roof with three sloping sides. It features four elements: a Romanesque rose window, a single Renaissance portal with the construction date of the building and the coat of arms of the consecrating bishop carved on its lintel, a marble niche with a bas-relief depicting the Virgin Mary enthroned with the Child and angels, and two stone lions on either side of the portal. The church is flanked by a three-story bell tower, built in the second half of the 12th century. The oldest part is the lower level, where two Roman-era inscriptions (1st century AD) are embedded in the walls, while the other two levels were added in the 15th century.
The interior of the cathedral originally had three aisles until the 18th-century renovations. Today, it consists of a single nave with side altars and the Chapel of the Blessed Sacrament (1627). The presbytery is raised above the crypt below. The wooden ceiling of the nave is adorned with paintings from 1655, with the central depiction of the Assumption of Mary. The dome ceiling of the presbytery is frescoed with a scene from Paradise (18th century), and the pendentives feature representations of the four evangelists. Of notable historical and artistic interest is the Tomb of Giulio Gallotti (15th century). Also worth mentioning are the funerary plaques of the three bishops Giacomo Lancellotto di Tropea, Nicola, and the noble Giacinto Camillo Maradei di Laino.
The crypt, as it appears today, dates back to the time of Roberto il Guiscardo. The vaulted ceiling is supported by fourteen columns made of marble and granite. At the entrance, there is a fresco depicting the Pietà (14th century). The last bishop of Policastro, Federico Pezzullo, is also buried there.
The stone church of Gamla Uppsala, built over the pagan temple, dates from the early 12th century. Due to fire and renovations, the present church is only a remnant of the original cathedral.
Before the arrival of Christianity in Sweden, Gamla Uppsala was the seat of Swedish kings and a ceremonial site known all over northern Europe. The settlement was home to royal palaces, a royal burial ground, and a great pagan temple. The Uppsala temple, which was described in detail by Adam of Bremen in the 1070s, housed wooden statues of the Norse gods Odin, Thor and Freyr. A golden chain hung across its gables and the inside was richly decorated with gold. The temple had priests, who sacrificed to the gods according to the needs of the people.
The first Christian cathedral was probably built in the 11th century, but finished in the 12th century. The stone building may have been preceded by a wooden church and probably by the large pagan temple.