No, a car is not only unnecessary for a tourist in Boston, it is often a major disadvantage. Boston is one of the most "walkable" cities in the United States, with many of its most famous landmarks—such as the Freedom Trail, Faneuil Hall, and the North End—all located within a few square miles of each other. Furthermore, the city is served by the "T" (MBTA), the country's oldest subway system, which provides high-fidelity access to Cambridge (Harvard/MIT), the Back Bay, and the Seaport. Parking in Boston is notoriously difficult and expensive, with hotel parking often exceeding $50 to $70 per night, and the city's historic streets are famously narrow and confusing to navigate (even with GPS). For trips outside the city core, such as to Salem or Concord, you can take the Commuter Rail or a seasonal ferry. Unless you are planning a multi-day road trip to the Berkshires or the Maine coast, you are better off relying on your feet, the subway, and the occasional rideshare.