Old Town is exactly how it sounds. This is a tourist town that has managed to preserve its old roots. The buildings look old. There are people singing on the street, vendors selling small items. There are candy shops selling old fashioned candy connjuring up bittersweet childhood memories.
There are gem stores, candle making stores, etc.
Everything contains that old town feel.
There is also some fabulously authentic mexican food restaurants.
The best time to go is during the day. This is not really a nighttime town and most stores are already closed.
This is a good place to take friends and family that are visiting San Diego.