The Line (in Arabic: ‎; in Spanish: La Línea) is an eco-city[1]​ planned by the government of Saudi Arabia to begin construction during the first quarter of 2021,[2]​ whose main premise is that it does not have streets or cars and, in addition, makes exclusive use of clean energy.[3]​.

In an international framework where renewable energies were gaining weight, one of the world's main hydrocarbon producers, Saudi Arabia, began to devise a strategic plan to diversify the business and begin to stop depending on oil. This objective, along with others, was part of the plan known as Saudi Vision 2030. This plan included the creation of a new economic zone, named NEOM, projected to be created in the Gulf of Aqaba of the Red Sea, due to its proximity to the borders of Egypt and Jordan. On the other hand, in 2018, the Saudi country was one of the most polluting countries in the world, emitting 624,987 kilotons of CO2.[4]​.

In January 2021, the Prince of Saudi Arabia, Mohamed bin Salmán, announced to the media the creation of the country's first city free of carbon dioxide emissions, with a linear design – hence its name – to avoid having streets.[3]​.

The project began construction on November 1, 2022.

Throughout history, as humans have needed to group together in larger numbers to live, relate, protect themselves or trade, different morphologies have emerged, such as the orthogonal plane, radioconcentric plane or the irregular plane. All of them have in common an expansion from their core or cores outward. In this case, one of the main characteristics is its linear shape. Specifically, and in order to create a completely pedestrian city without streets, it was decided to make it forming a completely straight line along 170 km through the desert, starting on the shores of the Red Sea. This particular shape, according to the prince himself, would also reduce the environmental impact on the environment, ensuring that "it preserves 95% of nature."[5]​.

Another particularity is the 3-level design, starting with the upper pedestrian layer, the first underground layer for services and the second and last layer where the high-speed transportation network will be located that would connect both end-to-end of the city. Through the official government account, it was ensured that compared to the usual morphologies of cities, adopting the rectilinear shape ensures that its inhabitants do not take, by ultra-fast transport, more than 20 minutes[6]​ to reach the furthest point of all, while at the same time, it would not take more than 5 minutes to walk to essential services.[7]​.