There are several towns close by Nuremberg that are easily accessible by public transport. The Nuremberg KulTour Ticket (available when you spend the night in any hotel in town) gives you two days' free travel on all public transport lines (including the great subway system) and free admission to sights around town.
Bamberg - Bamberg was ruled by a Bishop until Napoleonic times. There are beautifully carved facades on many of the religious buildings here, and Michaelsberg (a monastery) houses a beer museum that shows all the kinds ofequipment used over the centuries to create beer. Visit the beautiful Old Town Hall with its historic murals and check out the museum inside.
Erlangen -Erlangen has a lovely Old Town (Altstadt) marketplace and St. Martinskirche, a 13th century church with a 15th century wooden statue of St. Martin on horseback. Take in the palace gardens and the 18th century Kitzmann brewery. Make a trip to the tourism office in the Town Hall, then ride the elevator up to the 14 floor for a great view.