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Fact-check log

Checked on 15 November 2026, against the excerpts kept for this site. Where good sources disagree, both are kept.

Length

UNESCO’s Statement of Outstanding Universal Value gives the Great Wall a total length of more than 20,000 kilometres, built from the 3rd century BC to the 17th century AD as the military defence project of successive Chinese empires. [UNESCO] On 6 June 2012 the BBC, reporting state media, wrote that the wall measures 21,196.18 km (about 13,170.7 miles) based on the latest state survey results, as reported by the news agency Xinhua. [BBC News] Britannica’s “Top Questions” answer gives the total length of all sections ever built as about 21,196 kilometres (13,171 miles), including overlapping sections that were rebuilt, and the Ming wall as about 8,850 kilometres (5,499 miles). [Britannica] A UNESCO periodic report on the property gives the Ming Great Wall as 8,851.8 km, and gives the Great Wall of the Qin, Han and other dynasties as a separate figure. [UNESCO] The most extensive and best-preserved version, Britannica says, dates from the Ming dynasty (1368–1644) and runs for some 5,500 miles (8,850 km) east to west from Mount Hu near Dandong, in southeastern Liaoning province, to Jiayu Pass west of Jiuquan, in northwestern Gansu province. [Britannica] A preliminary study released in 2009, the BBC reported, estimated the wall to be 8,850 km long — a figure close to the Ming length given in the UNESCO periodic report, and not the later all-periods total. [BBC News] About one-fourth of that Ming length, Britannica says, consists solely of natural barriers such as rivers and mountain ridges; about 70 percent is actual constructed wall, and the small remaining stretches are ditches or moats. [Britannica]

The 2012 figure and the Ming figure are both used on this site. They are not treated as a correction of one another. The 2009 preliminary figure of 8,850 km sits with the Ming length, not with the later all-periods total.

One wall, or many

Encyclopaedia Britannica says the Great Wall actually consists of numerous walls — many of them parallel to each other — built over some two millennia across northern China and southern Mongolia. [Britannica] The BBC describes the Great Wall as a series of walls and earthen works begun in 500 BC and first linked up under Qin Shi Huang in about 220 BC. [BBC News] UNESCO’s official short description says that in about 220 B.C., under Qin Shi Huang, sections of earlier fortifications were joined together to form a united defence system against invasions from the north. [UNESCO] In the 3rd century BCE, Britannica says, Shihuangdi (Qin Shihuang), the first emperor of a united China, connected a number of existing defensive walls into a single system. [Britannica]

Ends of the line

That statement says the Great Wall begins in the east at Shanhaiguan in Hebei province and ends at Jiayuguan in Gansu province to the west. [UNESCO] Traditionally, Britannica says, the eastern terminus of the wall was considered to be Shanhai Pass (Shanhaiguan) in eastern Hebei, on the coast of the Bo Hai; later government-sponsored investigations revealed sections of wall in Liaoning, and the greater total length of the Ming wall was announced in 2009. [Britannica] The most extensive and best-preserved version, Britannica says, dates from the Ming dynasty (1368–1644) and runs for some 5,500 miles (8,850 km) east to west from Mount Hu near Dandong, in southeastern Liaoning province, to Jiayu Pass west of Jiuquan, in northwestern Gansu province. [Britannica]

Visibility

NASA’s 2005 feature “China’s Wall Less Great in View from Space” calls the idea a space-based myth: the Great Wall, frequently billed as the only man-made object visible from space, generally isn’t, at least to the unaided eye in low Earth orbit, and it certainly isn’t visible from the Moon. [NASA] The theory that the wall could be seen from the Moon, NASA writes, dates back to at least 1938, and was repeated until astronauts landed on the lunar surface. [NASA] Apollo 12 astronaut Alan Bean is quoted: “The only thing you can see from the Moon is a beautiful sphere, mostly white, some blue and patches of yellow, and every once in a while some green vegetation. No man-made object is visible at this scale.” [NASA] Kamlesh P. Lulla, then NASA’s chief scientist for Earth observation at Johnson Space Center, said it is very, very difficult to distinguish the Great Wall in astronaut photography, because the materials used in the wall are similar in colour and texture to the land around it. [NASA] Asked whether you can see the Great Wall from space, Britannica answers that you typically can’t: astronauts stated it was not visible with the naked eye from the Moon, and that the structure is only sometimes visible from low orbit and the International Space Station. [Britannica] UNESCO’s criterion (i) text still calls the Wall “the only work built by human hands on this planet that can be seen from the moon.” That wording is part of the official statement; later NASA writing, cited on the myths page, does not agree that it can be seen from the Moon. [UNESCO]

Condition

Only 8.2% of the original wall remains intact, with the rest in poor condition, according to the report as quoted by the BBC. The BBC does not spell out how “original” was defined. [BBC News] UNESCO records that the visual integrity of the Wall at Badaling has been impacted negatively by construction of tourist facilities and a cable car. [UNESCO]

Claims that do not appear in these excerpts — watchtower counts, un-sourced labour totals, or a single “true” length — are not used as facts on this site.