Dwelling compounds or quadrangles (Siheyuan) - the enclosed, one-story courtyard houses that make up old Beijing, feature a typical Chinese folk residential architecture.

A standard siheyuan usually falls into a rectangular compound with one-story houses squarely facing the cardinal points and a courtyard in middle.

A pair of stone lions usually stands in front of the vermilion studded door with painted lintel on the top. Decorative patterns are flowers and bird. Stepping over a high wooden threshold, you will find a stone screen standing ahead. It is built to avoid direct inspect from outside and also believed to dispel evil spirits. The next comes the outer courtyard, flanked by rooms to the east and west. These serve as kitchens and servants' living quarters. On the north end of the outer courtyard is the "Main House" southward for enough daylight with 3-5 rooms. The up-turn eaves provide a pleasant shade in summer. One room amid is for living or community purposes with a smaller bedroom or studies beside. Through two passages on each side of the Main House, one can enter the inner yard. Rooms on each side were for married children and their families. Greenery planted in the courtyard presents an inner garden.

Some large compounds have two or more courtyards, inhabited by an extended family with several generations. "Four Generations under One Roof", a novel by the contemporary writer Lao She, depicts Beijingers in the 1930s and 1940s living in siheyuan.

Beijing still has about 400,000 residential quadrangles now, mainly distributed over the East, West, Xuanwu and Chongwen districts. The municipal government has earmarked a number of dwelling compounds for protection.