Boston has 3 accessible airports: Boston Logan International (the main Boston-based airport), Manchester-Boston Regional (nearby in New Hampshire and the furthest away), and T.F. Green (nearby in Rhode Island). Manchester and T.F. Green are considerable farther away than Logan, but usually have cheaper airfares (it is worth looking into these options if you are budget conscious).
Boston is also accessible via the train at South Station, which is located along the red line in central Boston.
From Logan Airport, you can take the blue line subway (about 15 minutes to downtown) or the silver line bus (about 20 minutes to downtown) into the city for under $3. A taxi into the city will cost around $25-30 plus tip and can take anywhere from 10-45 minutes depending on where you are heading. You could also rent a car, but that wouldn't be my first recommendation because driving in Boston is horrendous, expensive, and confusing.
There is a shuttle bus to Logan airport from Manchester-Boston Regional that will be about 60-90 minutes and can cost around $70 (renting a car at this airport might not be a bad option). From T.F. Green, you can take the MBTA commuter rail to South Station, which will cost about $11.
There are taxis in Boston, but they are not easy to come by and they are pretty expensive. You can find them usually parked outside of hotels or taxi stands. Also be sure that you are in a legitimate taxi (usually white) and not a scammed cab. Car shares like Uber or Halo are the most convenient options.
You can get around Boston's harbor by using the water taxi that is at the waterfront. One-way tickets will vary depending where you are going, but generally cost about $10.
The public transit system, know as "the T" or the MBTA, is a very convenient and fast way to get around Boston if you don't have a car. Fares cost either $2.50 cash or $2 with a prepaid CharlieCard (or $2/$1.50 on bus) that you can purchase at some stations or retailers. Getting a CharlieCard is worth it if you think you will be hopping around the city via subway and bus (offers free transfers with the card). You can also purchase one-day or seven-day cards for $11 or $18.
Like I previously mentioned, driving in Boston can be a bit of a headache... So you can definitely rent a car here, but just know that it is not a normal mapped out city and the drivers have little patience.
Boston is a very walkable city. It is easy to get around by foot and it is better to be able to stop and see the historical architecture of the city.
