Somewhat off the blue tour - the kéktúra - on the yellow jerusalem pilgrimage route is the Pannonhalma Abbey with an impressive library. In the church there, some windows are made of thin light marble instead of glass, which lets in dull daylight.
The name of the abbey is like a play on words: Pannon-h-🍏 (alma = apple) So an Apple branch; -)
Pannonhalma is a more than 1000 year old Benedictine monastery, which is very picturesquely situated on a hill. It is worth paying the entrance fee and digging a little deeper into the history of the abbey. From Győr it is easily accessible by bike via cycle paths, good infrastructure (accommodation, restaurants ...) in the area.