Twenty-seven tunnels were built in the castle to store large quantities of food and weapons and to hold approximately 3000 soldiers. Wide and steep ramps were built on the east and west side to allow people to carry materials upward. The entire structure was built with massive bricks mortared together with special cement made from lime, sticky rice juice and tung oil. In order to guarantee the quality of the construction, every brick underwent a strict quality control process. The brick makers and builders were ordered to mark their names on each brick. Even today, it is possible to find Chinese characters and numbers on the bricks. No doubt, this detailed attention to quality of construction is one of the reasons why the condition of the castle remains so remarkably good today.

Source: TravelChinaGuide.com

Editor: Feng Hui