Although the western slope that the Cog Railway ascends is straightforward from base to summit, the mountain's other sides are more complex. On the north side, Great Gulf—the mountain's largest glacial cirque—forms an amphitheater surrounded by the Northern Presidentials: Mounts Clay, Jefferson, Adams and Madison. These connected peaks reach well into the treeless alpine zone. Massive Chandler Ridge extends northeast from the summit of Washington to form the amphitheater's southern wall and the incline is ascended by the Mount Washington Auto Road.