Google Maps:
http://goo.gl/maps/vJRFi

Free parking is available in the WGBH Visitors Parking lot adjacent to 1 Guest Street. Free parking is also available in the Brighton Landing Parking Garage; bring ticket to WGBH security for validation.

MBTA bus routes:
http://www.mbta.com/rider_tools/servicenearby/?sa=1+Guest+Street%2C+Boston%2C+MA+02135&findservice=Display+Routes

Hubway bike station:
38 Guest Street @ New Balance
http://www.thehubway.com/