A map showing the relevant parts of campus is available here (pops).

By Car:

From I-90 (Massachusetts Turnpike): Get off at Cambridge (exit 18). Turn left immediately onto Soldiers Field Road (west). Take Harvard Square exit, bear right across Anderson Bridge, and drive straight into Harvard Square.

Parking: On-street parking is scarce in Cambridge. There are public parking lots and garages, however, and the Harvard University Parking Office, 29 Garden Street, sells day passes in University lots for $5.

From Logan Airport:

By subway (the "T"): Take the shuttle bus to the AIRPORT T stop (BLUE LINE). Take the BLUE LINE inbound four stops to GOVERNMENT CENTER. Change to the GREEN LINE westbound and go one stop to PARK STREET. Switch to the RED LINE outbound (toward ALEWIFE), go four stops and get off at HARVARD. The subway ride from Logan Airport can take 45 to 60 minutes. A ticket costs $1.75(?).

By taxi: The ride to Harvard Square takes about 20-30 minutes, depending on traffic. Typically, the ride from Logan Airport to Harvard Square costs about $25.

From South Station (Trains and Buses):

By subway: Take the RED LINE toward ALEWIFE from South Station six stops to HARVARD.