Introduction to Agarwood Pavilion: Agarwood Pavilion, also known as the "Cool Hall", was the place where Emperor Ming of Tang Dynasty and Concubine Yang spent the summer and enjoyed the cool air in the Xingqing Palace in Chang'an during the Tang Dynasty. Beside the pavilion is a large waterwheel with a diameter of 18 meters and a weight of 10 tons. It is the oldest "air conditioner" in China.