Home to MIT, Harvard, and Tufts, Cambridge hosts a large, diverse population. Each area has its own special "feel" - with hip and trendy Davis and Inman Squares, biotech centered Kendall Sq or eclectic Central Sq amongst others.
For those who enjoy the outdoors, walk to the Charles River and wave across to Boston. Areas of Memorial Drive are closed to cars on Sundays so pedestrians and bikers can enjoy the river. There are boathouses at Kendall Sq and Charles River basin to rent out kayaks, canoes or sailboats. If you enjoy biking, ride the Minuteman Bikeway to Lexington and beyond. Runners have a multitude of possibilities (running map).
Cambridge hosts hundreds of excellent restaurants. Gastro-pubs are scattered all over, but try Green Street Grill in Central, Temple Bar in Porter, or Russell House Tavern in Harvard, amongst a multitude of others. Visit Julia Child's favorite Chinese restaurant at Mary Chung's, or try some authentic Taiwanese food at Mulan, both near Central. Or try the Japanese Market in Leslie University at Porter, with several small stalls. Cambridge also has excellent Indian, Thai and other ethnic cuisines.
For late night entertainment, clubs include Middlesex and The Enormous Room in Central. For those who love salsa or swing, try Ryles in Inman, or the Havana Club in Central. For movies, visit the Brattle Street Theater. For plays and theater, try the American Repertory Theater. If you like pool, try FlatTop Johnny in Kendall or Diesel Café in Davis.
There are numerous performances during the school year in all 3 undergrad campuses. Also visit the Harvard museums - it is amazing how much art and natural history is hidden in the back halls of the University!