Check out the calendar at CAV. This place is known for hosting some fantastic exhibits, music shows and other events.
You'll have no end of sightseeing choices when staying in Coimbra. CAV is a good place to begin here, but there are loads of other fine places to visit. Portugal dos Pequenitos, Old Cathedral of Coimbra, and Santa Cruz Church are close to the community arts facility and and will cap off your day nicely.