How was the Great Wall of China built? Being the first (new world) wonder of the world, the Great Wall of China is an astounding structure coming in at 13,171 miles long and an average height of 25.6 feet high. But how was this incredibly great structure engineered? Built over a period of about 20 years, the Great Wall involved about 800,000 laborers who were forced to do the task. These forced laborers made hard stones of packed earth stuck together with mud and sand. As you can imagine, this was a very difficult task, nearly half of the laborers dying throughout the wall’s construction. An incredible structure with a terrible history.