Cleveland Circle, Boston
Via Route 128: Route 9 East (towards Boston). Go approx. 4 miles. (You'll go through many lights, past the Chestnut Hill Mall on the left). At the 4 mile mark you should be a large intersection with roads coming from all directions. Get into the left turn lane. You'll turn left onto Chestnut Hill Ave. Although there are no signs to indicate this, you should see a fairly large green sign indicating "Cleveland Circle". Turn left here. Go approx. one mile downhill, and you're thrown into a large intersection, complete with MBTA Subway tracks. On your left will be Showcase Theaters and a Ground Round. Immediately after the Ground Round is the field on the left. You can turn left onto Beacon Street and look for parking.
Via Storrow Drive: Exit for Kenmore Sq.; Follow signs for Kenmore Sq. turn right and you'll be on Beacon St. At the huge Kenmore Sq. intersection, follow Beacon St. which will be the middle road "straight" through the intersection. Follow Beacon St. a few miles and several lights into Cleveland Circle and Cassidy Park. You'll notice the Ground Round and Showcase Theaters on the left. Look for parking. (If you see the Boston College Stadium, turn around!.)
Public Transportation: Green "C" Line to the end in Brookline at Cleveland Circle.
Field 1 is closest to the Ground Round, and Field 2 is closest to the reservoir and the Baseball field.
Use MapQuest to see more of the map.