The tulou clusters in the Fujian Province of China have been declared UNESCO World Heritage sites. A Tulou (Hakka houses) is an earthquake-proof fortified residential complex made with mud, sticky rice, brown sugar, bamboo, stone, and wood. The walls are 1.8-2.0 meters thick with just one gate. The structures are built in concentric circulars, rectangles, or squares. The tulou is designed so that it remains cool in the summer and warm in winter. It can be 3-5 stories tall and can accommodate up to 800 clan members, the largest tulou being the Chengqi Lou Tulou with 370 rooms. The lower floors consists of the common facilities and a central courtyard and the upper floors are living quarters.
