Throughout the Free State, March 25 is celebrated as Maryland Day, which commemorates the arrival of English colonists in 1634. But in College Park, Maryland Day is something else: a celebration of the state’s flagship university, when the campus opens its doors to the surrounding community, alumni or not. There are more than 400 activities taking place, from the football team’s spring game to an insect petting zoo. (“Imagine tarantulas, exotic insects, scorpions, bees and millipedes longer than your hand for you to look at and touch.”) Try making 3D art, conduct surgery with robots, listen to musical performances, explore rare books or sample ice cream from the Maryland Dairy. Saturday from 10 a.m. to 4 p.m. Free.