The basement runs the length of the block of buildings, and seems to be the combination of two separate areas, probably belonging to different buildings before Spade bought up the block and combined it. It’s a combination of dry, musty halls, rooms full of stuff, and ducts.
The larger area, directly under Cobb’s, consists of three separate chambers, one of which is full of pipes and whatnot, while the other two look like the image below – cluttered and piled high with all manner of things.
The other area, west of the main club area of Cobb’s – and probably under the garage – is made up of two chambers, both smaller than the three to the east. One is mostly empty, and is made up of very old brickwork, as below. The other is a cluttered room like the one above.