The Line (stylised THE LINE; Arabic: ذا لاين) is a conceptual linear smart city in Saudi Arabia in Neom, Tabuk Province, housed in a single building, that is designed to have no cars, streets or carbon emissions. The original plans called for the city to span 170 kilometres (110 mi) at a height of 500 m (1,600 ft) and a width of 200 metres (660 ft) sized to accommodate a population of 9 million (25% of Saudi Arabia's 2022 population of 35.5 million). The Line would have an entirely glass mirror exterior. The plan calls for all basic services to be within a five-minute walking distance.

The plan was announced in 2021. Saudi Arabia has stated that it aims to complete a 5 km (3.1 mi) central segment by 2030, while completion of the full 170 km (110 mi) project has been pushed to 2045. However, in 2024, the Wall Street Journal and Bloomberg both reported that the first phase will only be 1.5 miles. Saudi officials denied these reports and stated that the project was continuing as planned.

The city is one of the five announced regions of Neom and is a part of Saudi Vision 2030 project.

The Line is eventually planned to be 170 kilometres (110 miles) long. It could stretch from the Red Sea approximately to the city of Tabuk and could have nine million residents, resulting in an average population density of 260,000 per square kilometre (670,000/sq mi). By comparison, Manila, the world's most densely populated city in 2020, had a density of 44,000 per square kilometre (110,000/sq mi). The Line's design consists of two mirrored buildings with an outdoor space in between, having a total width of 200 metres (660 ft) and a height of 500 metres (1,600 ft). This would make it the third tallest building in the country after the Abraj Al-Bait Clock Tower and the proposed Jeddah Tower, and approximately the 12th tallest building in the world.

The plan is for the city to be powered entirely by renewable energy. It will consist of three layers, one on the surface for pedestrians, one underground for infrastructure, and another underground for transportation. Artificial intelligence will monitor the city and use predictive and data models to find ways to improve daily life for its citizens, with residents being paid for submitting data to The Line.

The estimated building cost is US$100–200 billion (400–700 billion SAR), with some estimates as high as $1 trillion. It is claimed by the Saudi government that it will create 460,000 jobs, spur economic diversification, and contribute 180 billion SAR (US$48 billion) to domestic GDP by 2030. According to Crown Prince Mohammed bin Salman in 2022, the first phase project is expected to cost SAR 1.2 trillion (US$320 billion), and the Saudi sovereign wealth fund Public Investment Fund (PIF) would provide half of the sum.

On 5 April 2024, Bloomberg News reported that the project had been scaled back as a result of restrictions over funding by the PIF. Bloomberg cited Saudi officials as expecting a 2030 completion of a 2.4 kilometres (1.5 mi) section of the city which would contain fewer than 300,000 residents, down from an expected 1.5 million.

The Line contains elements of architectural ideas from the industrial era.

• In 1882, the Spanish urban planner Arturo Soria imagined a linear city, based on innovative use of the tramway. He applied part of his idea to a neighborhood in Madrid but lack of support ended the scheme.
• In the 1950s, the French architect Yona Friedman proposed the concept of an integrated, modular and vertical "spatial city" to solve the problem of urban sprawl, but the idea remained an intellectual curiosity.
• In the 1960s, the Italian avant-garde group Superstudio presented a radical artistic project: the continuous monument, "an architectural model for total urbanization," which was supposed to cover the entire Earth, but without any feasibility or real utility. The proposal was a criticism of Modernism, monumentality, design and capitalism.

The first plan for The Line was announced on 10 January 2021 by Saudi Crown Prince Mohammed bin Salman in a presentation broadcast on state television. Earthworks began in October 2021, and crews working on the project were to move in during 2024. As of July 2022, the first phase of the project was scheduled to be completed in 2030. Bin Salman, as chairman of the Neom board of directors, released a statement and promotional video on 25 July 2021 which led to more widespread media coverage of the project. This caused questions to be raised about the merits of the design and environmental issues, with critics concerned that the project would create a "dystopian" and "artificial" facility that had already displaced the Huwaitat indigenous tribe and would impact the migration of birds and wildlife.

By October 2022 construction was under way, with excavation taking place along the entire length of the project. Saudi Arabia commissioned a SAR 700-million (almost US$190-million) concrete multi-plant factory capable of producing up to 20,000 cubic meters (roughly 700,000 cubic ft) of concrete per day. By October 2024 over 100,000 workers were preparing the initial grading, working around the clock.

The project management required all architects to sign confidentiality agreements, which is why there are no references to The Line on any of their websites. German newspaper Süddeutsche Zeitung learned that two architects had terminated their participation in the project because of human rights and ecological concerns, Norman Foster and Francine Houben from Mecanoo. The paper also reported that several high-ranking architects were still on board, David Adjaye, Ben van Berkel (UN Studios), Massimiliano Fuksas, the London office of the late Zaha Hadid, Rem Koolhaas, the Laboratory for Visionary Architecture (LAVA) as well as Delugan Meissl and Wolf D. Prix from Coop Himmelb(l)au. The Süddeutsche criticized the lack of sustainability and the double standards of the architects in moral issues. In November 2024 it was announced that Delugan Meissl and Gensler had been appointed as the architects for phase one of the project.

By March 2023, more than 4,500 piles had been driven in module 43, reaching a peak of 60 piles per day. Piling work then shifted towards modules 45, 46 and 47 located at the marina. Excavation of about 1 million cubic metres (35 million cubic feet) of earth was taking place each week at the marina.

The design includes a marina, twice the size of existing marinas, on the northern side of the buildings, away from the sea. The plan calls for a tunnel and canal to be made through The Line, large enough for large cruise ships to pass through. Construction started in April 2022, aiming to open to visitors and residents by 2030. As of February 2024 over 90 million cubic metres of material had been moved.

Early plans proposed an underground railway with 510-kilometre-per-hour (317 mph) trains that could travel from one end of The Line to the other in 20 minutes. As of 2023, short tunnels had been dug for the start of the railway and a train was in a prototype stage of development.

In April 2024 it was reported that the project had been "scaled back" after foreign direct investment investors had not "bought into the crown prince's vision", according to Torbjorn Soltvedt, principal analyst at risk consultancy Maplecroft. Fluctuating global oil prices had contributed to the decision.

The Line was expected to complete an initial section of 2.4 kilometres (1.5 mi) long by 2030, with a population of 300,000 rather than the intended 1.5 million.

The Saudi minister of economy and planning rejected the claims of scaling back. He said in an interview during World Economic Forum special meeting in Riyadh that "For NEOM, the projects, the intended scale is continuing as planned. There is no change in scale". As of October 2024, Saudi Arabia intends to complete a 5 kilometres (3.1 mi) central segment of The Line by 2030, while completion of the full 170 kilometres (110 mi) project has been pushed to 2045.

In an interview with Dezeen, associate professor Marshall Brown at Princeton University said he believed that in such large-scale urban planning, it would be difficult to achieve the slick, futuristic aesthetic seen in the concept art because of the large number of factors involved; for example, one of the images depicts a picnic on a 200-metre-high (660 ft) ledge, which would probably be dangerous in real life. Hélène Chartier of C40 Cities compared The Line to other unrealised linear city projects, such as the 1882 design by Soria and a 1965 proposal for a linear settlement in New Jersey. Dutch architect Winy Maas said that while he would love to live in such an environment, its profile as seen in the concept art was monotonous, and he believed it would facilitate unfavorable wind flow through the interior.

Philip Oldfield of the University of New South Wales said that the quality of life would probably come down to whether the city was well-managed, rather than to its visual flair. Oldfield said the project would have a carbon footprint of about 1.8 gigatonnes (2,000 million short tons) of CO₂ equivalent in the glass, steel, and concrete, because "you cannot build a 500-metre-tall [1,600 ft] building out of low-carbon materials". He said the 170-kilometre (110-mile) profile would create a large-scale barrier to adjacent ecosystems and migratory species similar to that created by highways, and the mirrored exterior facade would be dangerous for birds.

Researchers from the Vienna Complexity Science Hub suggested that a circular city of a 3.3 km (2.1 mi) radius would have had much shorter commuting times than a linear city. The average distance between two inhabitants of a linear city would be 57 km (35 mi), as opposed to 2.9 km (1.8 mi) for a circular city. In a linear city, each inhabitant would have only 1.2% of the population in walking distance as "people are as far away from others as possible", as opposed to 24% in a circular city. In a linear city, walking and cycling would not be popular and travel time in a fast train would be disproportionately long, while a compact circular city would allow active mobility and fast trains would not be needed. The required density in a circular city would be much lower, which would allow it to be built with existing technology, reducing the environmental footprint of buildings. A railway line disruption would immobilize a linear city, but have less impact on a circular city.

Digital rights researchers such as Vincent Mosco have suggested that the city's data collection scheme could make it a "surveillance city", because of arrangements that would distort consent to sharing data, and because Saudi Arabia's poor human rights record might imply potential misuse of data. Neom CEO Joseph Bradley said that the Neom coordinators were resolving privacy issues and that Saudi Arabia had a personal data protection law.

Aside from the merits of the projected city, there was also scrutiny of the actions of the Saudi government in pursuing the project. In October 2022, three men of the Howeitat tribe, Shadli, Ibrahim, and Ataullah al-Huwaiti, were sentenced to death when they refused to vacate their village as part of the NEOM project. Shadli al-Huwaiti was the brother of Abdul Rahim al-Huwaiti, who was shot dead by security forces in April 2020 in his home in Al-Khariba, in the part of Tabuk province earmarked for NEOM, after he posted videos on social media opposing the displacement of local residents to make way for the project. In response to reports of human rights violations, one company, Solar Winds, pulled out of the project in 2022.

According to architect and urban planner Etienne Bou-Abdo, "the 3D images presented are not classical 3D architecture images", and the designers of the project "have rather called upon video game designers". Bou-Abdo stated that the plan included "a lot of technology that we don't have today". Many of the project's key announcements, particularly in the areas of energy and transportation, were based on technologies that did not exist even in prototype form.

• List of Saudi Vision 2030 Projects
• Arcology
• King Abdullah Economic City
• Masdar City
• Palm Islands
• Prince Abdulaziz Bin Mousaed Economic City
• Saudi–Egypt Causeway – proposed bridge over the Straits of Tiran from Saudi Arabia to Egypt
• Jabal Omar development project

• Official website
• NEOM | THE LINE – New Wonders for the World on YouTube 25 July 2022 (release date)
• Saudi Arabia announces plans for the car-free linear city called The Line, 170 kilometers long as Part of Neom Project Archived 23 March 2021 at the Wayback Machine
• NEOM in Progress on YouTube 22 May 2024 (release date)