It really all depends on the location.
For public places, the local city or county government will control permits for shooting, though if you're doing a small enough shoot, you might not need to bother. It never hurts to ask your local government, either way.
Privately owned property is another story altogether. For offices, business locations, private parks, or any areas that aren't owned by the public, you need to contact the owner. Expect each owner to have their own rules. Some will let you shoot for free as long as you give credit. Others will charge an arm and a leg. It can vary wildly. Start calling around and asking to speak with building managers.
Also, give craigslist a try. They're typically a pretty popular place to look for filmmaking help, locations, etc.