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Measurement rules and structural terms recur across this site. Use this glossary to read rankings and engineering dossiers with confidence, from architectural height and vanity height to outriggers, mega-columns and tuned mass dampers.
The field follows the CTBUH’s category thresholds: generally over 150 metres for a skyscraper, 300 metres for supertall, and 600 metres for megatall. Bars are true to scale; the planned Jeddah Tower is shown dashed because it is not yet completed.
Only completed buildings enter the ranking. Merdeka 118 cleared the megatall mark at 678.9 metres in 2023; the earlier supertall titleholder, the Empire State Building, stood at 381 metres for 41 years.
Terms are listed roughly from measurement concepts to structural systems and construction methods.
The height measured from the lowest, most prominent open-air pedestrian entrance to the architectural top of the building. Permanent spires are included; antennas, flagpoles and other functional equipment are not. This is the measure used for the main ranking on this site.
The height to the very highest point of the structure, including functional equipment such as antennas. It is always equal to or greater than architectural height. A building can lead one measure and not the other.
The height of the topmost floor that is regularly occupied. It is usually lower than the architectural top because crown, plant and observation levels sit above.
The height of a public or semi-public observation level, where one exists. Not every tall building includes one, and it is often far below the roof.
An informal term for the share of a tower’s height that is unoccupied, such as a spire or crown. It helps explain why two buildings with similar roofs can rank differently.
The Council on Tall Buildings and Urban Habitat. Its height criteria and Skyscraper Center database are the reference used for many rankings, including the category rules followed here.
The CTBUH defines a skyscraper as a building generally over 150 metres tall. The cut-off focuses on buildings whose design, structure and economics are shaped by their height.
A skyscraper at least 300 metres tall. The CTBUH reserves "supertall" for buildings of 300 metres or more, a threshold first genuinely passed in the 1930s.
A skyscraper at least 600 metres tall, the CTBUH’s term for the current frontier. Only Burj Khalifa and Merdeka 118 are completed megatalls today.
A horizontal structural system, often one or more storeys deep, that connects the central core to perimeter columns or mega-columns. Outriggers greatly increase stiffness against wind and earthquake loads.
A horizontal truss around the perimeter of a building that ties columns together. Belt trusses are often paired with outriggers to distribute forces around the whole floor plate.
A very large perimeter column, often concrete-filled steel or heavily reinforced concrete, that carries very high axial loads and works with outriggers to resist overturning.
A large perimeter column used in a core-and-outrigger or braced-frame scheme. Super-columns and mega-columns describe similar ideas at slightly different scales.
The central vertical element, usually of reinforced concrete, that carries gravity loads and provides much of the building’s resistance to horizontal forces.
A structural system combining a stiff concrete core with outriggers and perimeter columns. It is one of the most common systems in supertall buildings.
A core shaped so that wings or lobes brace one another, providing torsional stiffness. Burj Khalifa uses this arrangement.
A steel frame in which diagonal members carry horizontal forces. Bracing can be concealed within a core or expressed on the exterior.
A steel frame in which rigid beam-to-column connections resist horizontal forces through bending. It is ductile but usually more flexible than a braced or core system.
A large-scale perimeter frame of mega-columns and diagonal or belt members that carries both gravity and lateral loads, often working with an internal core.
A system with an exterior framed tube and an interior core tube acting together. The exterior tube resists lateral loads much like a hollow cylinder.
Construction that combines steel and concrete so they act together, such as concrete-filled steel tubes or steel beams connected to a concrete slab.
A method that places concrete under compression using tensioned steel tendons after casting. It reduces deflection and allows longer or thinner spans.
A continuously moving formwork system used to cast vertical concrete elements such as cores. Concrete is placed in cycles as the form rises.
A self-raising formwork system that moves up with the building, often carrying working platforms, and is central to core construction in supertall towers.
A deep foundation element formed by drilling a hole and filling it with reinforced concrete. Piles transfer building loads to stronger ground or rock.
A thick reinforced-concrete slab that spreads building loads over a wide area, often transferring them to piles below.
The non-structural outer envelope of a building, usually glass and metal, that keeps out weather while carrying only its own weight and wind loads.
Two layers of envelope separated by a cavity, used for insulation, ventilation and solar control. Shanghai Tower uses this arrangement.
A large mass, often near the top of a tower, that moves to counteract wind-induced sway. It controls motion for occupant comfort rather than adding strength.
Wind-tunnel testing using a flexible model that can move, used to study how a specific tower shape responds to wind, including vortex shedding.
A step in the profile of a building where the floor plate reduces with height. Setbacks can change wind behaviour and align structural members.
A gradual reduction in the width of a tower with height. Tapering improves aerodynamic performance but changes floor spans and column positions.
A tapering vertical element that is part of the architecture. A permanent spire counts toward architectural height, unlike a functional antenna.
Definitions are written for a general audience and simplify specialist practice. Where a term has a precise technical definition, follow the linked engineering sources on each building profile.
See the terms applied: Burj Khalifa ↗