The glory years of the Boston Celtics may be behind them, but they can still offer an exciting game at the Boston Garden. The share the FleetCenter with:
The Boston Bruins, one of the oldest franchises in the NHL.
You can get to the Garden by subway: take the Orange Line or the Green Line to North Station (where commuter rail from the north and northwest ends up as well).
One of the most popular professional sporting events in Boston is the annual Boston Marathon, held on Patriots' Day - the Monday closest to April 19.
Hundreds of thousands of people line the race route from Hopkinton to Copley Square, 26 miles (and 385 yards) away. Truth be told, however, most people come not to see the professional runners, who are mostly by you in a flash, but to cheer on the thousands of amateurs who also run the race. Prime viewing spots near the finish line can be hard to come by; however, you can have just as much fun watching the race in places such as Washington Square in Brookline and Cleveland Circle on the Brookline/Brighton line (both accessible via the C, or Beacon Street, branch of the Green Line trolley).
The Boston Red Sox had one of the most famous losing streaks in major-league sports; which they finally broke in 2004 (hooray!). They play in Fenway Park, home of the Green Monster in left field and one of the best (and, alas, most expensive) places to see a baseball game. Fenway is also one of the smallest baseball stadiums in the country, so even aside from the sheer fanaticism of local fans, tickets can be hard to come by (in 2005, almost all tickets sold out the day they went on sale). Fenway is easily accessible from the Kenmore Square stop of the Green Line trolley; if you do drive, count on spending $20 to $25 for parking on Boylston Street (way more if the Yankees are playing).
The New England Patriots have won Super Bowls in 2002, 2004 and 2005. A fan could get used to that. They play in Gillette Stadium, 30-40 minutes south of Boston on Rte. 1, accessable via both car and special commuter-rail trains.
The New England Revolution of Major League Soccer play in Gillette Stadium, south of Boston.
Suffolk Downs is the Boston area's only horse track.
Just a mile from Logan Airport, it's accessable via the Blue Line subway (Suffolk Downs stop).