Some parts of the Great Wall have crumbled over the years, but giving the fact that it has endured at least 365 years of storms,winds, floods, etc, proves that it is a pretty sound structure. Most of the eroding sections in the wall have been repaired or replaced, but it is a very painstaking process to make it blend in with the rest of the wall. Every few hundred yards, there are watchtowers. These towers were used to spot anyone who was trying to infiltrate the wall. They used to be inhabited by at least one imperial soiler at a time. Today, these towers are no longer used for observation, but instead they are used for adventurous tourists.

One of the most visited sections of the Great Wall is on Mount Badalng, near Beijing. The wall here is 35 feet (11 meters) tall, 25 feet (7.6 meters) wide at the base, and 20 feet (6 meters) wide at the top. Its watchtowers are 100 yards -200 yards (91 meters -180 meters) apart along the wall, standing at 40 feet (12 meters) high.

In the east, the Great Wall slithers through the Mongolian Border Uplands. That part of the wall has a granite foundation, sides of stone and brick, and is filled with earth (dirt, mud, gravel, etc.). To the west, the wall winds through hilly land, bordering a desert. That part of the wall is made of earth and water, and tends to crumble more.