Forbidden City - Ten Amazing Facts - as part of the travel series by GeoBeats. 10 - Imperial home of 24 Chinese emperors for over 500 years. 9 - No one could enter or leave without permission. 8 - There are 980 buildings and nearly 10,000 rooms. 7 - World's largest collection of ancient wooden structures. 6 - It took 15 years to build the complex. 5 - Hundreds of thousands of workers were used. 4 - Roofs are yellow since that's the emperor's color. 3 - Over a million artifacts are housed here. 2 - The complex spans 720,000 square meters. 1 - The Last Emperor, Puyi, was designated this title at the age of 2.