In Roman times (I - IV century A.D.) Cairate probably was a vicus, a village, with small sanctuaries or precincts where arae (altars) were dedicated to gods (1). Some inscriptions of Roman times are preserved in the monastery. Archaeological excavations led to the discovery of traces of a Roman rural house (villa) below the monastic rooms located on the terracing looking on the Olona river valley. In the part under the monastery church there are the remains of the granary of the villa, where cereals and legumes were stored for trades along the road connecting the Olona valley to Milan and the alpine valleys.
The area changed aspect during the V and VI centuries: a necropolis gradually set up, some objects from the grave goods found are shown. It is possible to date at the same period the few but clear traces of a small funerary church: the foundations of the apse and some burials inside and outside it (2). Probably the so-called “Manigunda sarcophagus” (3) belonged to this group of burials. Manigunda is the legendary founder of the monastic complex. According to tradition she was a Lombard noblewoman who, after drinking the water of the source of Bergoro (a village neighbouring Cairate) and recovering from illness, would decide to found the monastery as an act of thanksgiving and to dedicate it to Saint Mary of the Assumption. During the XV century the learned humanist Tristano Calco witnesses the discovery in this building of a sarcophagus containing the remains of a woman with a golden dress, gold fibulae and waistband. Maybe it was just this sarcophagus with the remains of Manigunda.