The Hospital
An abbey of this size needs a hospital in which a monk well-versed in herbalism mixes and applies ointments, tinctures and poultices. Here, of course, the large library also benefits the brothers, for the ancient tomes contain a wealth of prescriptions, many of which have been forgotten for centuries.
There are, of course, limits to the healing skills of the monks in the hospital, and the graveyard is located nearby - but that is another story...