The main house of Katsura is divided into three main parts:  Old Shoin, Middle Shoin, and New Palace.  All three are connected in a zig-zag pattern, from the southeast to the northwest, and you can walk from one to the next without ever leaving the house.  However, not all three units were built at the same time.  The Old Shoin, the first of the three main buildings which make up the main house of the Katsura Detached Palace, was built under the auspices of Prince Toshihito, the first head of the Hachijô family, and could perhaps be a revised version of the "little teahouse in the melon patch" built around 1616.  The Middle Shoin was built later by Prince Toshihito’s heir, Prince Noritada, around 1641.  Also at this time, the Old Shoin was reconstructed into its present form.  In about 1655, Prince Sachi, a son of the ex-Emperor Go-Mizunoo, was appointed heir to the Hachijô family line.  At this time, the New Palace was first constructed.  Later, the New Palace continued to be changed some time around 1663. Akira Naito writes that, "The three sections of the main house reflect the shift from the shoin style of the late middle ages to the sukiya style of the early Edo period—a historical transition that led to the development of modern Japanese residential architecture."