Plainridge Park is operated by PENN Entertainment. Harness racing and simulcast wagering have been taking place at Plainridge since 1999. It is also the oldest active place to make a bet in the Bay State. However, one destina.Plainridge Park Casino in Plainville is the only racetrack and slots parlor in Massachusetts. There are countless options available, both online and in-store, making it difficult to know where to start. If you’re a diamond lover, you know that finding the perfect diamond can be an exhilarating and daunting task. Small casino, not so great reward program for a frequent gambler, employ not very knowledgeable slot techs or managers. All things to do in Plainville Commonly Searched For in Plainville Casinos & Gambling in Plainville Popular Plainville Categories Things to do near Plainridge Park Casino Explore more top attractions.