The National Building Museum’s Big Build is on Saturday, Oct. 12, 10 a.m. to 4 p.m. It is an interactive, fun-for-all-ages celebration of our built environment. Learn from construction and building arts professionals while hammering nails, sawing logs, applying join compound, hopping aboard real trucks, and more. This is a free drop-in program. No reservation necessary. The National Building Museum is at 401 F St. NW. nbm.org.