Yes on the Trolley Tour. I believe there's a "hop on/hop off" option. It will allow you to get the highlights of the city which will help you decide what you might want to explore further. Please note that in this area we don't measure distance in terms of miles but in terms of time. Where are you staying? That will help determine how long it will take you to get places. Lexington and Concord are full of Revolutionary War history, Lowell has a long mill city history, Salem has it's witches and haunted houses, Rockport and Gloucester teem with shops, sailing and our fishing culture, and many of the towns are just very pretty to drive through. Oh, forgot about Minuteman National Park in Lexington & Concord. How much time depends on how thoroughly you like to explore. You can touch the highlights in a few days but if you want to explore allow at least a week, if not more.