I just want to share our experience with others. We were in Pisa about two weeks ago for a stop on our way to CT. We had planned to check our bags at the train station, but the bag check was on strike so we had to take them to the tower with us. NOTHING SAYS TOURIST LIKE ROLLING YOUR SUITCASE BEHIND YOU. We got on a bus to the tower, and we saw pickpockets in action on the woman in front of us and warned her. We made it to the tower with everything in tact.
When we went to get on the return bus, there was a group of young teenage girls standing at the bus stop. They worked in a band. Some of the girls pushed to the front, boarded the bus and then stopped with us on the steps. The other girls worked from behind. We had two suitcases and my camera bag, so no free hands and they were on us. The girl unzipped my camera bag, and a man on the bus slapped her. Fortunately most everything was in my husband's money belt, but the girl was brash enough to stick her hand in my husband's pant pocket. As the bus was ready to leave, the jumped off and waited for the next group of luggage rolling tourists.
Thankfully we didn't lose a thing, but it was a situation where even with the best eyes, we were at risk.
Unfortunately, there was no alternative for stowing the luggage at the station. There were lockers, but they were out of order.