section_path: Course
section_name: Course
paragraph_text: Course
  
  A formal definition of what constitutes a "Great Wall" has not been agreed upon, making the full course of the Great Wall difficult to describe in its entirety. The defensive lines contain multiple stretches of ramparts, trenches and ditches, as well as individual fortresses.
  
  In 2012, based on existing research and the results of a comprehensive mapping survey, the National Cultural Heritage Administration of China concluded that the remaining Great Wall associated sites include 10,051 wall sections, 1,764 ramparts or trenches, 29,510 individual buildings, and 2,211 fortifications or passes, with the walls and trenches spanning a total length of 21,196.18 km (13,170.70 mi). Incorporating advanced technologies, the study has concluded that the Ming Great Wall measures 8,850 km (5,500 mi). This consists of 6,259 km (3,889 mi) of wall sections, 359 km (223 mi) of trenches and 2,232 km (1,387 mi) of natural defensive barriers such as hills and rivers. In addition, Qin, Han and earlier Great Wall sites are 3,080 km (1,914 mi) long in total; Jin dynasty (1115–1234) border fortifications are 4,010 km (2,492 mi) in length; the remainder date back to Northern Wei, Northern Qi, Sui, Tang, the Five Dynasties, Song, Liao and Xixia. About half of the sites are located in Inner Mongolia (31%) and Hebei (19%).