The state of these many, many large structures varies from 'frequently used' to 'completely abandoned until the end of time.' Which one each falls under can generally be determined by how many windows are broken, how much security is in the area, and whether or not there are any theft-worthy goods within. Even the warehouses that don't get used for commerce have found purpose, however, usually from squatters just seeking shelter for the night... and, occasionally, a vigilante or villain looking for a place to hide.