Traditional Chinese houses called siheyuan along with hutong alleys make up much of the culture and housing in Beijing. Siheyuan houses form communities around courtyards, with gates typically facing southeast according to feng shui beliefs. Inside, rooms surround the central courtyard without original indoor plumbing. Today, high-rise apartments predominate in Chinese cities, including luxury buildings and low-income housing, while newer suburban developments consist of gated communities with security systems for upper middle-income residents living in western-style units with modern amenities.