STEAM Saturday at the National Building Museum offers hands-on, family-friendly activities focused on science, technology, engineering, art, and math, typically held on the second Saturday of each month from 10 AM - 12 PM (or 1-3 PM), allowing kids (grades 2-6) and caregivers to design, build, and problem-solve, often linked to current exhibits like Brick City, and it's free with museum admission.