The first documentary reference to Santa María de Piasca is a donation from 930 making reference to a basilica just founded on the site. Little over a decade later, in 941, an agreement was recorded between 36 nuns and an unknown number of monks under an abbess Aylo, telling us that the monastery housed a community of both sexes. The monastery's dual character faced several oscillations, with the nuns leaving and returning twice. The archeological evidence of the original monastic buildings shows a small single nave church and separate spaces for the two groups.
A foundation stone records that the current church on the site, the Romanesque edifice, was dedicated in 1172 under a prior Petrus Albus. By this point the monastery had been incorporated into the larger Cluniac monastery of San Facundo y Primitivo de Sahagún (in 1122) and brought under the Benedictine Rule. The inscription also names the master of the project as Covaterio. The church has two sculpted portals, the west and the south. The portals have most likely been somewhat reconstructed, possibly with elements exchanged between the two. The triple arcade on the west façade has obviously been renovated as the central sculpture of Mary is from the sixteenth century. The two apostles (Peter and Paul) to her sides may have originally flanked an image of Christ, forming, as Ruth Bartal suggests, an abbreviated apostolado.
References:The Clementinum is a historic complex of buildings in Prague. Until recently the complex hosted the National, University and Technical libraries, the City Library also being located nearby on Mariánské Náměstí. The Technical library and the Municipal library have moved to the Prague National Technical Library at Technická 6 since 2009. It is currently in use as the National Library of the Czech Republic.
Its history dates from the existence of a chapel dedicated to Saint Clement in the 11th century. A Dominican monastery was founded in the medieval period, which was transformed in 1556 to a Jesuit college. In 1622 the Jesuits transferred the library of Charles University to the Klementinum, and the college was merged with the University in 1654. The Jesuits remained until 1773, when the Klementinum was established as an observatory, library, and university by the Empress Maria Theresa of Austria.