Great Wall is a technology unique to the Chinese that can be researched at the Castle in the Castle Age in Age of Empires II: The Forgotten.
This technology will increase the Hit Points of Walls and Towers by 30%.
Strategy
Great Wall is an excellent technology in games where walls are important or when performing a turtling tactic. With it researched, Chinese walls become the best in the game, even better than the Byzantine ones since Chinese also can research Masonry and Architecture , and Byzantines doesnยดt ( totaling 50% Hp plus +2 armor, +2 pierce armor, +6 building armor if the 3 Technologies are researched). The tower boost is useful as well, especially on water maps to help ward off ships. However, as it costs 200 stone to research, it is often better to go without unless there are a lot of Walls and/or Towers it would affect.