In 1929, trustee Thomas Cochran, Class of 1890, purchased and gave to the school 125 acres of wooded land, stating, "It would be my ideal to make this a natural piece of ground intersected by paths and adorned by ponds and trees, by birds and wild flowers." Today, the sanctuary, named for Cochran's brother Moncrieff, Class of 1900, is precisely what Cochran dreamed, a place of quiet solitude and natural beauty. In spring, summer, and fall, the paths of the sanctuary are used by walkers and joggers, and in winter by cross-country skiers. PA's cross-country course passes through the sanctuary, and in one section of the woods PA has set up a ropes course used by Outdoor Pursuits. The gated entrance to the sanctuary is located between Nathan Hale and Fuess houses, at the end of Chapel Avenue.