The history of Saint Cugat begins in Roman times. The most significant archaeological remains are dated in the Late Roman Imperial Period (probably at the beginning of IV century), when a fortification was constructed. This building probably had a squared shape (40x40m2) with walls 5m wide and circular towers (diameter=8 m) every 14m.
The first clear documented evidence of the existence of a monastery at this location does not appear until the IX century. In 986 a new abbot started an ambitious architectural program that included the construction of a church, a cloister and the refurbishment of several pre-existing buildings. Both the damages produced by the Arab raids and the increasing power and wealth of the institution could be the reason behind this decision. At mid-XI century these works, all of them in Romanesque style, were finished. In the last quarter of this century, the construction of the bell-tower was then started. The work kept uncompleted until the XVIII century.
The church (and the rest of the monastery) was again importantly damaged in 1114 due to an Almoravid raid. Some years later (mid-XII century) a major rebuilding program started. Its construction was started from the apse in Romanesque style, with a central nave and two aisles. It is important to note, that both the first and the second churches, where constructed using the base of the roman walls as their foundations. This detail explains many of the building’s currently existing problems.
The works advanced at a high rate and in the period 1205-1211. At this point, works were stopped for unknown reasons. This pause is the cause why the temple has two differentiated parts: the first one (built up to 1211) entirely constructed in Romanesque style. The second one, resumed in 1251, entirely constructed in Transition Gothic style.
In the years following 1251 the octagonal tambour was finished and works on the remaining parts of central nave and aisles were continued. At the beginning of XIV century a fourth nave in the meridional facade was built. The temple was finally finished in 1337.
After the conclusion of the building, the decadence of the monastery started. It lasted for the following centuries (mid-XIV to XVIII). Between 1427 and 1429 several earthquakes struck Catalonia. There is no documentary evidence of damages in the Monastery of Saint Cugat itself.
The decline situation slightly changed in the XVIII century. Notices of renovations and conservation works are found in the monks’ registers. In 1749 it is registered that the cloister had risk of collapse. It is then reported a bad historical stability of the cloister’s soil condition, with an increasing bad state due to the construction of an upper floor in the XVI century.
The monastery was abandoned in 1835 due to the Desamortización de Mendizábal (law which intended to expropriate lands from the Catholic Church in order to redistribute them among peasants).
After 1835, the church kept its functioning as parish. In the final decades of the XIX century several campaigns have been performed to inspection and restoration of Saint Cugat: 1879-1881 by Villar y Lozano and Rogent to repair important cracks that were reporting in different elements; 1902-1910 several remaining important works were undertaken; in the 70’s cracks in the four main facades of the church were detected, and monitoring with plaster was applied; in the 1990’s by the Architectural Heritage Service of the Generalitat de Catalunya under the direction of architect Alfred Pastor Mongrell the masonry walls were reinforced and connected with their foundations; finally in 2014 the intervention focused on the removal the mortar in the joints susceptible to fall in the future.
ARCHITECTURAL FEATURES AND GEOMETRY
The monastery was built as a religious community, composed by a cloister and the church attached to the South-east wall. The church is a hybrid building, not as robust as a Romanic temple but neither as slender and diaphanous as the Gothic ones.
The church is composed by four naves, three polygonal apses built over the foundations of the Castrum Octavianum, an octagonal tambour, a bell tower and a sacristy. The church measures 50m from the apses to the facade and 20m in width, taking into account only the three main naves. The three main naves are separated in the area next to the transept by four octagonal columns circumscribed by a circle of 3m. In the area next to the entrance the columns become more slender reaching a 2.40m width. The average high of the central nave and the tambour are respectively 18m and 23m. The fourth nave was added at the beginning of the XIVth Century.
The facade of the church features a huge central rose window, more than 8m diameter. Besides this, two additional small roses exist on the facade. These are repeated along the top of the arches that divide the main nave from the lateral ones. In coincidence with the slender columns belonging to the Gothic period pointed arches can be seen and separated from the Romanesque arches (semicircular). All along the South-east wall and acting as a division between chapels there are three masonry buttresses plus two external ones acting in the south-west corner of the church.
The ceiling of the naves is characterized in the Gothic side by cross pointed vaults and in the Romanesque one by semicircular vaults which simulate to be cross vaults due to the presence of ornamental ribs that are not working as such. At the same time, in the fourth nave the chapels are covered by false vaults belonging to the Baroque period. Finally, an octagonal tambour from the Gothic period is located in the crossing transept. The octagonal base rests over four arches.
DAMAGES AND DIAGNOSIS
The most probable reason behind the appearance of vertical cracks in different sections of the northern wall separating the church from the cloister is the presence of differential soil settlements.
Several vertical cracks next to the main window in the apse could have appeared because the apse is founded over the old Roman foundation. In fact, the identified vertical cracks appear in the exact point where discontinuity between the two structures exists.
Longitudinal cracks in several vaults of the main nave and right lateral aisle have been classically named “Sabouret cracks” and its appearance is common in many medieval churches. The phenomenon behind the formation of the cracks is explained by the deformation compatibility between the membrane and the wall. The arch would tend to deform due to the nave’s configuration and excessive applied loads, but it is prevented from doing so due to the wall next to it. Thus, compatibility cracks appear in the membrane.
It seems evident that the detachment of some mortar from the vaults is related with the lack of compatibility between the ancient mortar and the cementitious one used in this intervention.
 P. Vivo i Gili, El Monestir de Sant Cugat a partir dels monjos i enllà: dades per a la història. Barcelona: Mediterrània, 2006.
 J. Auladell i Serrabogunyà, Obres en el temple de l’ex-Monestir (1833-1914). Sant Cugat del Vallès : Parròquia de Sant Pere d’Octavià, 1996.
 P. L. Artigues, M. Blasco, E. Riu Barrera, and M. Sardà, “Fortalesa romana, la basílica i el monestir de Sant Cugat del Vallès o d’Octavià (Catalunya). Les excavacions de 1993-1995, La,” 1997.
 Album pintoresch-monumental de Catalunya : Associació Catalanista d’Excursions Científicas,.
 G. Via, M. S. Isabel, R. Turró, and S. De Mar, “Modificació del Pla Especial de Protecció del Patrimoni Arquitectònic.”
 J. Ambros i Monsonis, El Monestir de Sant Cugat del Vallès. Oikos-Tau, 1985.
 A. Pastor i Mongrell, “Les Darreres restauracions del monestir de Sant Cugat del Vallès,” GAUSAC, vol. 16, pp. 11–23, 2000.