The current site of the Home Brewery isn’t very impressive; demolished for a parking lot and union hall, the land now sits empty. The caves, filled-in during the mid-Twentieth Century, surely still lie below the ground, filled with the rubble of the brewery they served. I would love to buy the land and excavate it if finances allowed.
Update: See the Engine Co. No. 3 from August of 2018 here.
Above, to review, is the Sanborn map of the brewery, and below is the Compton and Dry view of the rectangular block on which the brewery sat. If you look closely, there is a large sinkhole right under the brewery. Perhaps the brewers discovered the caves through the sinkhole? Or perhaps, the natural depression in the rock allowed for the easy construction of lagering cellars. As you can see, there are other large sinkholes throughout the area as well, pointing to the intricate system of underground rivers that carved out the subterranean world of South St. Louis.
Note the close proximity to the Marine Hospital from an earlier post.