Rock Creek Heritage Day is Saturday, and the event will celebrate the complete rehabilitation done on Peirce Mill. For the first time in more than 20 years, the mill will turn and once again grind grain. The festival runs from 10 a.m. to 4 p.m. and will feature demonstrations of arts, crafts and trades that took place on the Peirce family estate in the mid-to-late 1800s, along with period music. From 6 to 8 p.m., park rangers will conduct candlelight tours of the mill (free tickets required). The mill is located on Tilden Street Northwest near the intersection of Beach Drive and Park Road. For information, go to nps.gov/rocr.