Magazine Beach is an American riverside park in Cambridge, Massachusetts. It is located on the left bank of the Charles River, across Memorial Drive from Cambridgeport, and opposite Agganis Arena and other Boston University facilities on the far bank. The park's namesake, a gunpowder magazine from 1818, is in the park. It is the oldest building in the Charles River Reservation. There was a swimming beach at the park in the early and mid 20th century, attracting about 60,000 swimmers in a season, but swimming in the Charles River became dangerous due to pollution, and was forbidden in 1949.