Violent crime in Boston is rare but do be wary of pickpockets, scam artists, and car thieves. As in any large city, use common sense, especially after dark. Stay with the crowds and walk on well-lighted, busy streets. Take cabs or park in well-lighted lots or garages.
Subways and trolleys are safe, but stay on your guard. Don’t take unmarked taxis or any taxi that lacks a posted photo ID of the driver. The MBTA has its own police officers (who patrol stations and monitor them via video); don't hesitate to ask them for help.