The Jeddah Tower in Saudi Arabia, once called Kingdom Tower, is planned to be the first 1-kilometer-tall building. As of November 2026, if completed, it would be the world's tallest building or structure, at least 180 meters taller than the Burj Khalifa; the CTBUH lists its height as 1,000 meters or more. Work on the Jeddah Tower halted in January 2018, when about one third of the tower had been built; it restarted in January 2025. As of November 2026, construction has passed the 120th floor and a height of over 482 meters (1,581 feet), and completion is expected around mid-2028. The CTBUH defines a project as On Hold when construction work has halted but there is an intent to complete the original design later, and as Under Construction once site clearing is done and foundation or piling work has begun; these status terms decide which list a stalled tower belongs on.
The Jeddah Tower is designed with a Y-shaped plan and a smooth taper; the CTBUH says this shape will significantly reduce structural loads by avoiding the complicated outrigger transfers and belt trusses that a setback approach needs. Its structure is all cast-in-place reinforced concrete walls, coupling beams and plate floors. The Jeddah Tower has to stand on soft bedrock and porous coral rock, which normally could not support a skyscraper without settling; a foundation design from 2013 calls for 270 bored piles up to 110 meters (360 feet) deep. In May 2008, soil tests cast doubt on whether the Jeddah site could support a skyscraper of the proposed one-mile height, 1,600 meters, and the project was reported as scaled back by up to 500 meters.
Height to the tip and height to the architectural top can give different rankings. From 2015 to 2021 Shanghai Tower was second tallest by height to tip. Merdeka 118 then passed it for second place with its much longer antenna spire, even though Merdeka has fewer floors and a lower highest occupied floor than Shanghai Tower. Shanghai Tower is organized as nine vertical zones, each rising from a sky lobby, a light-filled garden atrium that works like a town square. Some structural engineers define a high-rise as any vertical construction for which wind is a more significant load factor than earthquake or weight. By that measure, a building is tall when wind becomes a bigger structural problem than weight or earthquakes.
A skyscraper has to support its own weight, resist wind and earthquakes, and protect its occupants from fire; it also has to be easy to reach on the upper floors and supply utilities and a comfortable climate; the problems are considered among the most complex in design because of the balance between economics, engineering and construction management. New techniques have let skyscrapers become slimmer while getting taller. They include mass dampers to reduce vibrations and swaying, and gaps that let air pass through the building and reduce wind shear. Fazlur Khan's tube systems also let towers take shapes other than rectangular boxes. The Burj Khalifa's Y-shaped plan reduces wind forces and makes the tower easier to build; each wing has its own high-performance concrete core and perimeter columns, and the wings buttress each other through a six-sided central hub; the result, SOM says, is a tower that is extremely stiff torsionally.
A tall building also creates a stack effect: air moves inside it because the inside and outside temperatures differ. At the Burj Khalifa, the CTBUH says the building was designed to passively control these forces, which reduces the need for mechanical means of pressurization. The CTBUH's Height and Data Committee exists to set, and when needed refine, the official height criteria; it meets regularly to discuss developments in the tall building industry, possible changes to the criteria and, occasionally, particular buildings that are so complex that they need close evaluation to decide their height or category. The CTBUH sorts structures by material; a mixed-structure building uses distinct systems, one on top of the other, such as steel over concrete; a composite building combines two or more materials in its main structural elements, for example steel columns with concrete floors or a steel frame with a concrete core; the Burj Khalifa is listed as steel over concrete.
Height limits can come from planning rules, not only from engineering. London's St Paul's Heights policy, in operation since 1927, restricts high-rise development at certain sites when it would block protected views of St Paul's Cathedral and other historic buildings. As of November 2026, twenty cities in the world have at least a hundred skyscrapers taller than 150 meters (492 feet), most recently Singapore, Hangzhou, Moscow and Toronto in 2025. Skyscrapers are a common feature of city centers, especially in the Americas, Asia and Australia, often because land is limited and demand for space is high. In China, supertall construction took off in the 2010s: China overtook the United States to become the country with the most supertall buildings; the first supertall outside the United States was the Bank of China Tower in Hong Kong in 1990, and the first in mainland China were CITIC Plaza in Guangzhou and Shun Hing Square in Shenzhen in 1996.
The Great Pyramid of Giza stood 146.6 meters (481 feet) tall when it was new and was the tallest human-made structure for more than 3,700 years. Most of its smooth limestone casing was later removed, so it is now 138.5 meters (454.4 feet) tall. A tower can only count as a building if at least half of its height has rooms people can use, so radio and TV towers that are mostly empty frame do not make the list. As of November 2026, the Burj Khalifa in Dubai is the tallest building in the world, at 828 meters. As of November 2026, the CTBUH lists the Burj Khalifa at 828 meters to the architectural top, 829.8 meters to the tip including its antenna, and only 584.5 meters to the highest occupied floor. Which number counts depends on which question is asked, and the CTBUH keeps three separate records.
Words to know
- torsionally: against twisting
- atrium: open central hall
- outrigger: extra bracing arm
- composite: mixed materials
