The Great Wall of China extends over 8,850 kilometers from northeastern to north-central China, including trenches and mountains in addition to a collection of wall sections. The main series of walls stretches from Shanhaiguan in the east to Lop Lake in the west, roughly outlining the southern border of Inner Mongolia.
Although the east-west distance is estimated at this 8,850 kilometers, all of the individual lengths of wall in northern China added together exceed 50,000 kilometers. Beijing itself is home to about 13 different lengths of wall that are among the best preserved. Portions of the wall are disappearing due to disrepair, erosion and destruction.