Maybe some of those tunnels were where the better qualities of Prosecco sparkling wines or perhaps even the Brunello di Montalcino Reds were stored.
Or perhaps even the cask of amontillado?
CC
It'll be interesting to see how many more are down there. Probably served as storage for weapons and powder and such, along with being transit routes. I don't think the Sforza dynasty lasted all that long, but was living large while it did.