Lucca is a walled medieval city boasting one of the most well-preserved walls in Italy. The wall itself dates to the 1400s, but most of the city was built/rebuilt after that. Lucca is situated about 25-30 minutes from Pisa on the A12 and is one of the few medieval towns in Italy not built on a hill.
The thing which I will remember most about Lucca is the city's center - there are no cars or even bicycles allowed from 11-4, so it was very tranquil. I have fond memories of walking past pastry shops, bakeries, butchers, and cheese shops and being intoxicated by the odors which wafted across my nose. A good day trip for anyone in Tuscany on vacation or otherwise.