Boston Logan International Airport: Take the free Silver Line SL1 from your terminal to South Station (roughly 20–30 minutes). It is the best default: no airport-rail shuttle, no tunnel driving, and a free transfer onward to the Red Line; pick up a CharlieCard/contactless payment setup at South Station for later T rides. A taxi or rideshare is sensible only for a late arrival after T service ends (around 12:30am) or with several people and heavy bags; downtown fares are commonly about $25–50 before tip and surge. Do not choose a rental car for a city stay.
South Station (Amtrak, MBTA Commuter Rail, intercity buses): You arrive in the useful part of downtown: the Red Line, Silver Line, buses and the Harborwalk are at the station. Downtown Crossing, the Waterfront, Chinatown and the Financial District are walkable; Back Bay is a short Red/Orange Line connection or taxi ride. This is the principal arrival station for Amtrak’s Northeast Corridor services.
Back Bay Station (Amtrak and MBTA Commuter Rail): Take the Orange Line directly from the station for Downtown Crossing/Haymarket or toward Jamaica Plain; Copley, Newbury Street and much of Back Bay are an easy walk. It is the handiest rail arrival for Back Bay hotels, but not for the waterfront.
North Station (Amtrak Downeaster, MBTA Commuter Rail): North Station sits beside TD Garden and has immediate Green and Orange Line access. Walk to the North End in about 10–15 minutes; use the Orange Line for downtown rather than a cab if you are not hauling luggage. It is the practical arrival point from Maine and the northern suburbs.