The Attic of Joy, alternatively called the Pavilion that Forgetting to Fly and the Waterside Pavilion, was rebuilt in 1870 on the eastern lakeside of the garden. The government official once worked here were surprised at the attractive view and believed that "if the birds saw the view here, they would have so much joy that they could forget how to fly". That was the origin of the name. In the 1930s, this attic once served as one of the offices of the Military Affairs Commission, one of the most powerful organizations in Nationalist China.