The church has a Latin cross floor plan, with a single nave of ten metres in span and 45 metres in length, covered with five-section ribbed ogival vaults and a two-section transept. The presbytery is heptagonal in plan, with an ambulatory around the high altar with a baldachin, which was destroyed in July 1936. The interior is reminiscent of Flemish Gothic architecture, but is fitted with different elements that take you back to the eclectic architecture of the early 20th century: it uses parabolic arches and materials such as brick and artificial stone, especially in the ambulatory. The walls of the church have magnificent windows decorated with stained glass, also reminiscent of medieval architecture. The cloister is more than 30 metres square, with arcades that combine exposed brick on the columns with artificial stone at the base and capitals and arches, also in brick, with a egmental profile. Some elements of the old monastery were reused for the new work, such as some capitals and the Valencian tiles for the chapterhouse. The origin of the monastery of Valldonzella is the hermitage of Santa Margarida, a small Romanesque church exactly like that of Santa Maria de Valldaura and next to a country house, located in a wooded valley in the Collserola mountain range, still known as the Torre de Santa Margarida. It belonged and still belongs to the parish of Santa Creu d'Olorda, depending on the bishopric of Barcelona, where very close by, Bishop Berenguer de Palou, who gave the land for the house of the Valldonzella hermitage, had and still has the tower known as the Bishop's Tower together with another country house, on the border of the municipalities of Sant Feliu de Llobregat and Sant Just Desvern. Thus, the foundation of the Cistercian monastery is recorded on 4 November 1237. Between the two dates mentioned above, there is news of the incorporation of several women into the community, although the rule they followed is not specified. The first community was formed by Berenguera de Cervera with 11 nuns. Due to the insecurity of Valldonzella in 1263, the community obtained permission from Jaume the Conqueror to move to Barcelona, outside the city walls, to the place called Creu Coberta, which actually took place in 1269. The move was made because it was believed that the monastery was in a lonely, dangerous and rugged place. The community, or part of it, must have opposed the move, as seems to be demonstrated by the legend of the opposition of the image of the Virgin in the new place. This monastery was very important in the following years and its community was very extensive and was made up of the daughters of the families of the city's nobility. It was highly favoured by Jaume I and his successors and by the bishops of Barcelona, who joined the parish of Sant Esteve de Parets (1291) and Santa Creu d'Olorda (1416) to it. In 1308 it had 35 members. As proof of its prestige in those times, in 1395 King Joan the Hunter was to have a residence there, and in 1410 Martí the Humane fell ill and died, and a few years later, his widow Margarita de Prades retired there. It was also used as a residence by King Fernando the Catholic during his stays in Barcelona, given that it was located on the road between Barcelona and Sants, and therefore in the direction of Valencia and Zaragoza, and the Portal de Sant Antoni became the gateway for the kings to enter the city. The reform of the Council of Trent greatly affected the life of the monastery, insisting on enclosure and prohibiting the entry of more novices, until the prohibition was attenuated by Rome in 1599 thanks to the intervention of Felipe III. During the Reapers' War (1640-1652), the nuns left the monastery and moved to the city. In the last year of the war, during the siege of Barcelona, the monastery was completely destroyed. In 1674, the community moved to live in Santa Maria de Natzaret, a priory attached to Santa Maria de Poblet, located in the street that later received the name of Valldonzella. In 1814 the nuns had to take refuge in Mataró while the convent building was partly destroyed and rebuilt in 1826. In 1835 they had to leave the monastery again due to the disentailment law that forced religious orders to abandon their belongings. In 1847, the few surviving nuns of the exclaustration were reunited and resided there until 1909, when the events of the Tragic Week of Barcelona forced them to take refuge in the Torre dels Pardals in La Sagrera, owned by the Valls i Martí family. Like many other religious buildings, the convent was destroyed by fire. Work on the new convent began on the cloister and the surrounding outbuildings. In April 1913, work began on the provisional chapel, but the definitive church was not inaugurated until April 1919 and consecrated in 1922. Finally, in 1913, on the advice of Bishop Torras i Bages, the monks moved to the present site of Bellesguard, in a new monastery designed by Bernardí Martorell. On 19 October 1911, they bought a valuable 15th-century choir stall in the monastery of Sant Cugat, which is still in good condition. The church was dedicated to the Assumption, and today the community is made up of nine nuns, who, following the 'ora et labora' rules, offer a hostelry service and do bookbinding work.

Church with modernist façades made with a mixed apparatus of exposed work and masonry. It is formed by a central nave and two lateral ones with a Gothic structure. Inside there are paintings of boys and girls by Mauri for the altar of Sant Josep de Calassanç with sculptures by Juventeny and three polychrome alabaster reliefs (1945-1949); altar of the Virgin of the Pious School with a carved image of Claudi Rius (1945-1952); altar of Sant Pompili with an image of Fàbregas (1947); and Sant Benet altar, designed and painted by Joan Pàres (1950-1951). The foundation stone was laid on May 25, 1924. On May 1, the church was blessed, although it was not finished, as the main façade and the bell tower, which was supposed to be 40 metres high, are missing. He acted as an assistant to the future Sabadell architect Vila Juanico, as well as the local mason Simó Piera, who was the one who received Le Corbusier on his visit to Sabadell. Nicolau Molina was in charge of the stone, and the church was built by J. Espanyol with the help of Vinyas.