If you have history with Nashville, you probably remember a time before 12th South was safe, O'Charley's was the only local restaurant, and breweries didn't exist (to be fair, Gerst was a local brewery, but the tanks had been dry for a long, long time and Blackstone was more of a restaurant and Bosco's is closed). But other than those, breweries didn't exist.
Then, some upstarts from Mississippi opened the big, creaking doors in Marathon Village and Yazoo was born. In the tiny tap room, hordes of people sucked down a limited selection of beer in the terribly insulated room. Lines spilled out of the door. Volunteers were gifted a case (or two) for help during bottling pushes.
In no time, more breweries popped up. Today, every neighborhood as a local spot and many have more than one. If you love beer, this is a great time to be in Nashville.
If you want to try them all, take out of town friends on a tour, or just get up to speed, here is a good resource.