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 1st Saturday of each month of the school year, 3pm - 5pm. Every 2nd Saturday of each month of the school year, 10am to 3pm. Every 3rd Saturday of each month of the school year, 10am to 3pm.