The Chinese have worked on the Great Wall for thousands of years. In fact, they are still working on the wall today when it needs repaired. Each emperor that came to power added pieces to the wall to protect their dynasty. It wasn't one solid wall. It was a bunch of separate pieces.
Emperor Qin (Chin) did a great deal of work on the wall. He wanted a better barricade to protect his people from invaders. He wanted a wall 30 feet wide and 50 feet tall. He used farmers, captured enemies, criminals, slaves - and put them all to work building the Great Wall. Workers were not usually paid. Many people in China worked on the wall. Some historians say over a million people possibly worked on it.
It was dangerous work. Rocks fell on people, walls caved in, people died of exhaustion and disease. Workers were often only fed enough to keep them alive. There is an old Chinese saying, "Each stone in the wall represents a life lost in the wall's construction." This building project continued long after Qin's death. Most of the wall Qin constructed has crumbled and fallen down. The wall we see today was built later mainly during the Ming dynasty, but the idea of one day having a continuous wall for protection is credited to Emperor Qin.
The building of the wall continued for many years until the wall was over 4000 miles long. Today, parts of the Great Wall still stand. Tourists (approximately 160 million a year) visit portions of it that are open to the public. The money they pay for their ticket is used to maintain and repair sections of the wall. Many parts can be dangerous and need to be fixed.