There are many warehouses in Oakland!
Some are abandoned, some store things, some have functional industry in them, some have artists in them, some have hackers in them, some have squatters in them, some have been renovated and have apartments or businesses in them.
Oakland has a lot of warehouses because of our history as an industrial city. Our history as a post-industrial city means that many of the warehouses are vacant or have been repurposed for new businesses (typically in the "new" maker industries) or as homes.
The places where you're most likely to find warehouses are in many parts of West Oakland, along the estuary, and farther East.
Sometimes warehouses are next to vacant lots.