Who constructed the Great Wall? What difficulties did they face?

Quin Shi Huang constructed the great wall of china, He faced many difficulties, since he was the first emperor.

The Chinese constructed the "Great Wall of China." Some difficulties they had to face was possible invasion whilst they were vulnerable and focused on building the wall, invading animals, foreign lands, malfunctions with the building materials, (great stone blocks,) and possible death, since they were building in sometimes treacherous conditions.