Walking down the hill West of the Buddha Tower, through "Moon Gate", you get to the area known as the "Through a Picture Scroll". In this area you find the "Long Corridor", a 795-yard corridor built in order to protect the emperor from the sun. This is the longest Corridor in China!
Along the Long Corridor is the entrance to the main palace buildings. You need an extra ticket to enter this area, but the cost is well worth it. The main constructions in this area are the "Cloud Dispelling Hall" and the "Pavilion of Buddhist Fragrance".