Want to come visit, build and explore -- after-school or on the weekend? We have several (free!) drop-in programs for you to visit. During these programs, we open our doors to the community, where scientists of all ages can explore our space at no cost. Every Tuesday after-school at Excelsior Site (Every Tuesday of the school year, 3pm - 5pm). First Saturday at Bayview Site (Every 1st Saturday of each month of the school year, 10am to 3pm). Second Saturday at Mission Site (Every 2nd Saturday of each month of the school year, 10am to 3pm). Third Saturday at Excelsior Site (Every 3rd Saturday of each month of the school year, 10am to 3pm).