This year’s walk will again be led by Linda McElroy, Trail Through Time site specialist. Visit the Nashoba Brook stone chamber, view its interesting interior, and learn about its history and that of its associated square foundation. Time permitting, visit the Industrial Era site of Acton’s Pencil Factory. Meet at 10 a. m. at the parking lot at the end of Wheeler Lane off Route 27, North Acton. Wear hiking boots, bring bug spray and flashlight. About 1.5 to 2 hours, 1.5 miles round trip. In case of rain or poor trail conditions on October 20, the walk will be held Saturday, October 27, at 10 a.m. Call Acton Memorial Library (978-929-6655) for information or weather update; free.