Regulated City. Chang'an was a planned and highly regulated city. Internal walls divided the city into more than one hundred smaller quarters, mainly for safety reasons. Each quarter had gates that operated according to curfew. Gates were opened in the morning and closed and locked at night. Soldiers on horseback patrolled the streets and people had to remain indoors. City government sustained a complex system of drum towers that proclaimed the time. Local officials, in order to collect taxes and recruit soldiers, forced the residents to register in each quarter.

Government Offices. South of the palace were offices of the imperial government, including buildings that held the meetings of six boards: revenue, civil appointment, rites, works, punishments, and war. The emperor met with the chiefs of these six boards to discuss significant state affairs. Other departments were responsible for...