New building with a similar system to housing. This building would give you a room you can place items in for storage. It would be tiered and you can NOT place item hooks in it.

Tiers:

1 (2 2x2 boxes, a bag hook, 2 tool hooks (like the ones you can put on bags)

2 (Chest, 2x2 box, a bag hook, 3 tool hooks, [possibly] a profession's workbench? [like a carpentry thing])

3 (2 Chests, 2 bag hooks, 3 tool hooks, a profession workbench

4 (2 Chests, 2 2x2 boxes, 2 bag hooks, 4 tool hooks, 2 profession workbenches)

5 (3 Chests, 3 bag hooks, 5 tool hooks, 2 profession workbenches)

To prevent this from being too overpowered, you can't place any sort of wall hook in the room, only the storage you get from the room itself.

basically a heavily upgraded lockbox