The old Benedictine monastery of Sant Cugat gave its name to the town it presides over. The complex consists of the church, the two-story cloister located on the northern side, around which the chapter house and the old monastic outbuildings are arranged. The old abbey house is on the NW side of the monastic enclosure. The entire complex, of which subsidiary buildings have disappeared, located especially to the east of the cloister, was surrounded by a fortified enclosure of walls and towers (built between 1380 and 1383), which are largely still preserved. It was built on top of an earlier temple from the 5th century, of which we can see the remains in the cloister. The church is a building with three naves, without a transept, and three apses with a raised semicircular plan inside, and a polygonal one outside with columns on the edges and a frieze of arches with sculpted permodules. It has a dome covered with an octagonal dome on false shells, above the second of the five sections into which the naves are divided. Since its construction lasted two centuries (from the 12th to the 14th century), the initial Romanesque conception was gradually replaced by the Gothic style, a fact that is particularly evident in the vaults that cover the temple: still Romanesque in the apses, with purely ornamental veins in the sectors of the naves closest to the apses and of the Gothic cross in the rest of the church. Gothic solutions were also adopted in the ground plan, by placing the three lateral chapels on the south side, following the bell tower (with a Romanesque base, but completed later), as a fourth nave. The sculpture of the keystones, imposts and corbels from where the nerves start also reveal this transition. The façade, with the cover and the rose window, already presents a fully Gothic style. The cloister is undoubtedly the most outstanding element of the complex. The lower galleries are Romanesque, covered with barrel vaults, a d formed by semicircular arches that support double columns. We know that this lower cloister was built around 1190 by Master Arnau Gatell or Cadell (whose name appears on a capital), who is known to have lived in the monastery at least until 1207. The 72 pairs of capitals, with a single abacus each and a very elementary moulding, develop various themes: ornamental, with scenes from the Holy Scriptures, and with themes of everyday life. These capitals (some of which are characterised by small angular towers) can be related to those of the cloister of the Cathedral of Girona and to some of the cloister of Sant Pere de Galligants, in the same city. In the second half of the 16th century, a second floor was built with semicircular arches on slender Renaissance-style Tuscan columns. The chapter house was later transformed into the Chapel of the Blessed Sacrament. Part of the monastic outbuildings were destined to the Catalan Government's furniture restoration centre for many years. They now house the Monastery Museum. The old abbey house, transformed in 1736, now serves as the rectory. Inside is the 13th century image of Our Lady of the Forest, from the hermitage of Sant Adjutori. The excavations carried out between 1931 and 1936 in the enclosure of the cloister and in some parts of the church uncovered remarkable remains of a Roman fortification, the "Castrum Octavianum", which was a Roman fortress located near the imperial road that linked the Pyrenees with Tarragona, and that justify the story of Sant Cugat, who according to tradition was martyred there. A "martyrium" has also been uncovered, around which tombs appeared, and which was later enlarged (5th-7th centuries). Remains from the pre-Romanesque period are preserved on the northern wall of the cloister, as well as the foundations of the church and the cloister built in the 11th century. The origin of the monastic community of Sant Cugat is unknown. There is evidence of the existence of a well-organised monastery from 878, which, later with Abbot Donadéu (904-917) and his successors, reached a great level in terms of patrimony expansion, while playing a first role in the restoration work of Vallès and Penedès. Devastated by the incursion of Almansur (985), it soon recovered. The monastery continued in full splendor until the middle of the 14th century, when it began to decline. At the end of the 19th century, the architect Elies Rogent began restoration work there. Since then, several conservation and restoration campaigns have been carried out. Today, remains of towers located at the extreme corners of the circuit are preserved.