Where can I change old dollars?

Excuse me, could you please tell me where I could go to exchange my old dollars? I have a stack of bills that are no longer in circulation and I'm not sure what the best place to trade them in for new ones is. I've heard some banks might accept them, but I'm not sure if that's always the case. Are there any specific places or institutions that you would recommend? I'd really appreciate any guidance you can provide. Thank you!