The three large public parks in the Greater Boston Area that are riding destinations are the Middlesex Fells, Lynn Woods and Great Brook Farm State Park.  Members of Greater Boston NEMBA have been actively involved with these parks throughout NEMBA's history.  There are other large riding desinations that are in reasonably close proximity to Boston that are managed by NEMBA members affiliated with other chapters.  Some of these parks include:

Blue Hills Reservation - SEMASS NEMBA
Harold Parker State Park - North Shore NEMBA