The Museum Storeroom can be accessed through the door from the Staff Barracks.
The Museum Storeroom holds the Distilling Station. This can be used to replicate drinks for the Reserve Vintages display listed below. There's also a large Wine Rack, connected to your supplies via the Craftloot system. Behind this is some random crap, a button, and a model of how the Museum used to look. There's also a portal here to enter the debug room.