The trailhead is on the Cabot Trail at the base of North Mountain. The hut sits at the beginning of the loop, and the path is the only permitted way into this protected old-growth forest, so stay on it to avoid trampling the ground. The official estimates differ slightly, at 15 minutes for the trail and 20 for the sightseeing walk; allow 15 to 20 minutes.
For a photo, keep the stone path in the foreground and the hut above it. That gives you the rough stone walls, layered roof and forest setting in one frame.