Kloster St Gallen
Eventually, St Gall set up a hermitage in what is now St Gallen, in eastern Switzerland. This was the site that would later become the Abbey.
St Gall is often depicted with a bear companion. According to legend, St Gall's holiness was so great, that when confronted with a wild bear, instead of attacking him, the bear brought him firewood and remained his companion for life.
Bear iconography still exists in St Gallen, and although the abbey has not been active for two centuries, its cathedral is still an important place of worship.
Today the monastery is perhaps most famous for its Stiftsbibliothek, a library that holds one of the world's largest collections of manuscripts from the medieval period and earlier. The room itself is a sight to behold, immaculatly bound volumes line wooden shelves under a breathtakingly ornate ceiling. The floors are so delicate that visitors have to wear slippers to enter the room. No photos are allowed, but you can see pictures here. The library also has a virtual catalogue that gives access to much of their collection.
This library is a treasure trove of medieval rarities including the Plan of St Gall, which is the only existing architectural plan from the Middle Ages. A document on five pieces of parchment sewn together, it's a description of a monastery, complete with church, gardens, dormitories, industrial buildings, bake and brew houses, etc. It was never carried out, nor does it seem to actually correspond to the terrain of St Gallen, so instead it's interpreted as an example of an ideal monastic complex (digital copies of the plan and 2D and 3D renderings here).
There is also this excellent 9th century Irish poem about Vikings, written in the margins of a Latin grammar book (you can see a digitized copy of the book here).
The Abbey of St Gallen is also the namesake of the delicious St Galler Klostertorte. Although a written version of the recipe didn't appear until 1947 when the abbey was no longer in use, it is possible that some version of this cocoa cousin of the Linzer Torte had been made in the monastery bakehouses.