In architecture, a core is a vertical space used for circulation and services. It may also be referred to as a circulation core or service core. A core may include staircases, elevators, electrical cables, water pipes and risers.

A core allows people to move between the floors of a building, and distributes services efficiently to the floors. A core may also serve a key structural role in a building, helping support it and acting as a load-bearing structure with load-bearing walls.^[1][2] Cores in office buildings tend to be larger than those in apartment buildings because office buildings need to handle more traffic with an increased number of elevator shafts.^[3] It is generally desirable for a core to be as small as possible to maximize floorspace within the building.^[4] The core of a building is often placed in the center of a building, but it can also be placed on a side of a building, and there can be several cores in a building. Cores on a side of a building are known as perimeter cores, are completely inside the building and can allow for more uninterrupted, column-free floor space within a building. Offset cores are similar to perimeter cores but sit partially or completely outside a building. Cores split into several smaller cores are called mixed cores. A large portion (over 40&) of offset core buildings were built after 2010. An offset core can also be used to provide shade from the sun.^[5][6]

• Buttressed core
• Skyscraper design and construction