Pisa is reckoned a safe place to walk around and enjoy outside of area around the railway station at night as in many big cities. However, if you feel the need to ensure security the following page will provide you with some measures to do it:  http://www.lifeinitaly.com/travel/safety-tips.asp

Useful numbers

Police Station (Via Lalli 3; tel. 050583511).

Carabinieri 112 (Pisa Porta A Mare; Via Conte Fazio 43; tel. 050501779).