This is a nice park with swimming, fishing, easy mountain biking, and some climbing. There is a small entrance fee in summer, but it is free the rest of the time.
There are two boulders and a 35' slab behind park HQ and a big boulder on the main park road. They are of excellent quality.
You can approach this from Route 85 north of Hopkinton center (~45' west of Boston) or south from Route 9. It is 2.5 miles either way, the park entrance is signed. The HQ is just south of the main park 1/4 mile.
Mountain Project's determination of some of the classic, most popular, highest rated routes for Hopkinton State Park: