The Karakoram Highway , also known as the KKH, National Highway 35, N-35, and the China–Pakistan Friendship Highway, is a 1,300 km (810 mi) national highway which extends from Hasan Abdal in the Punjab province of Pakistan to the Khunjerab Pᴀss in Gilgit-Baltistan, where it crosses into China and becomes China National Highway 314. The highway connects the Pakistani provinces of Punjab and Khyber Pakhtunkhwa plus Gilgit-Baltistan with China’s Xinjiang Uyghur Autonomous Region. The highway is a popular tourist attraction and is one of the highest paved roads in the world, pᴀssing through the Karakoram mountain range, at 36°51′00″N 75°25′40″E at maximum elevation of 4,714 m (15,466 ft) near Khunjerab Pᴀss. Due to its high elevation and the difficult conditions under which it was constructed, it is often referred to as the Eighth Wonder of the World. The highway is also a part of the Asian Highway AH4.

The Karakoram Highway, also known as the Friendship Highway in China, was built by the governments of China and Pakistan. It was started in 1962, completed in 1979 and opened to the public in 1986. Pakistan initially favored routing through Mintaka Pᴀss. In 1966, China, citing the fact that Mintaka would be more susceptible to air strikes, recommended the steeper Khunjerab Pᴀss instead.  About 810 Pakistanis and about 200 Chinese workers died, mostly in landslides and falls, while building the highway. Over 140 Chinese workers who died during the construction are buried in the Chinese cemetery in Gilgit. The route of the KKH traces one of the many paths of the ancient Silk Road.

On the Pakistani side, the road was constructed by FWO (Frontier Works Organisation), employing the Pakistan Army Corps of Engineers. The Engineer-in-Chief’s Branch of the Pakistani Army completed a project documenting the history of the highway. The book History of Karakoram Highway was written by Brigadier (Retired) Muhammad Mumtaz Khalid in two volumes. In the first volume, the author discusses the land and the people, the pre-historic communication system in the Northern Areas, the need for an all-weather road link with Gilgit, and the construction of Indus Valley Road. The second volume records events leading to the conversion of the Indus Valley Road to the Karakoram Highway, the difficulties in its construction, and the role of the Pakistan Army Corps of Engineers and their Chinese counterparts in its construction.

The highway, connecting the Gilgit–Baltistan region to the ancient Silk Road, runs approximately 1,300 km (810 mi) from Kashgar, a city in the Xinjiang region of China, to Abbottabad, of Pakistan. An extension of the highway southwest from Abbottabad, in the form of the N-35 highway, meets the Grand Trunk Road, N-5, at Hasan Abdal, Pakistan.

The highway cuts through the collision zone between the Eurasian Plate and Indian Plate, where China, Tajikistan, Afghanistan, and Pakistan come within 250 km (160 mi) of each other. Owing largely to the extremely sensitive state of the Kashmir conflict between India and Pakistan, the Karakoram Highway has strategic and military importance to these nations, but particularly Pakistan and China.

On 30 June 2006, a memorandum of understanding was signed between the Pakistani National Highway Authority (NHA) and China’s State-owned ᴀssets Supervision and Administration Commission (SASAC) to rebuild and upgrade the Karakoram Highway. According to SASAC, the width will be expanded from 10 to 30 m (33 to 98 ft), and its transport capacity will be increased three times its current capacity. In addition, the upgraded road will be designed to particularly accommodate heavy-laden vehicles and extreme weather conditions.

China and Pakistan are planning to link the Karakoram Highway to the southern port of Gwadar in Balochistan through the Chinese-aided Gwadar-Dalbandin railway, which extends to Rawalpindi.

On 4 January 2010, the KKH was closed in the Hunza Valley, eliminating through traffic to China except by small boats. A mᴀssive landslide 15 km (9.3 mi) upstream from Hunza’s capital of Karimabad created the potentially unstable Attabad Lake, which reached 22 km (14 mi) in length and over 100 m (330 ft) in depth by the first week of June 2010 when it finally began flowing over the landslide dam. The landslide destroyed parts of villages while killing many inhabitants. The subsequent lake displaced thousands and inundated over 20 km (12 mi) of the KKH, including the 310 m (1,020 ft) long KKH bridge 4 km (2.5 mi) south of Gulmit.

It is highly questionable whether the lake, which reached 27 km (17 mi) in length in 2011, will drain. Goods from and to further north were transported over the lake by small vessels, to be reloaded onto trucks at the other end. In July 2012, Pakistan began constructing a revised route around the lake at a higher elevation with five new tunnels, with a total length of 7.12 km and two new bridges. The work was contracted out to the China Road & Bridge Corporation (CRBC) and was completed in September 2015.

At 806 km (501 mi) in length, the Pakistani section of the highway starts at Abbottabad, although the N-35 of which KKH is now part, officially starts from Hasan Abdal. The highway meets the Indus River at Thakot and continues along the river until Jaglot, where the Gilgit River joins the Indus River. This is where three great mountain ranges meet: the Hindukush, the Himalayas, and the Karakoram. The western end of the Himalayas, marked by the ninth highest peak in the world, Nanga Parbat, can be seen from the highway. The highway pᴀsses through the capital of Gilgit–Baltistan, Gilgit, and continues through the valleys of Nagar and Hunza, along the Hunza River. Some of the highest mountains and famous glaciers in Karakoram can be seen in this section. The highway meets the Pakistani-Chinese border at Khunjerab Pᴀss.