Quadrangle Courtyard, also named Siheyuan, is a historical type of residence that a courtyard surrounded by four buildings. The four buildings of a quadrangle courtyard are normally positioned along the north-south and east-west axes. The building located to the north and facing the south is considered the main house. The buildings adjacent to the main house and facing east and west are called side houses. Since the capital founding in Beijing in Ming Dynasty, quadrangle courtyard has been existed with palaces, government offices, streets, lanes and hutongs.

The layout of the building courtyard, is the north-south vertical axis symmetrically arranged and closed independent courtyard as the basic characteristics. According to its scale, the simplest one is the one front door courtyard. There are also courtyards with two, three or more front doors. The doors are lined in vertical axis.

Although quadrangle courtyard is residential architecture, it contains profound cultural connotations, being the carrier of Chinese traditional culture. It pays attention to geomantic omen that all of the choice from settlement site to orientation should be based on the geomantic theory.