Why do they call the Great Wall of China 'The Great Wall'?

Answer 1

The wall is deserving of its English title because of its size : it is the longest wall in the world. Although many sections are missing or in disrepair, the wall stretches for a length of 4000 miles (6400 km). The actual Chinese names for the Wall reflect this. "Long fortress" or "Wall of 10,000 Li" ( 1 Li being about .5 km). In Chinese history, the Great Wall played an important role in preventing the central plain from nomadic invasions. From that standpoint, it also deserves the adjective 'great' in its name.

Answer 2

The Great Wall gets it name because of its size. It is one of the largest man made structures on Earth.

It was built in primarily for defense against hostile attack.

There are different sections which were built at different times.