In which country is most of the Great Wall located?

Most of the Great Wall is located in China.

The Great Wall is a connected system of fortifications built, rebuilt, and maintained across northern China over many centuries. Earlier walls existed before the Qin dynasty, but Qin Shi Huang ordered major sections to be linked after unifying China around 221 BCE. Later dynasties extended or reconstructed parts of the network.

The best-preserved and most visited sections were built during the Ming dynasty, especially between the fourteenth and seventeenth centuries. These sections commonly use brick and stone and include watchtowers, passes, and signal stations.

The wall did not form one perfectly continuous barrier, and it did not reliably stop every invasion. It served several purposes, including border defense, communications, troop movement, and control of trade routes. The popular claim that it is visible from the Moon with the naked eye is false.