Design and facilities

Male and female prisoners are typically kept in separate locations or separate prisons altogether. Prison accommodation, especially modern prisons in the developed world, are often divided into wings. A building holding more than one wing is known as a "hall".

Amongst the facilities that prisons may have are:

• A main entrance, which may be known as the 'gatelodge' or 'sally port' (stemming from old castle nomenclature)
• A chapel, mosque or other religious facility, which will often house chaplaincy offices and facilities for counselling of individuals or groups
• An 'education facility', often including a library, providing adult education or continuing education opportunities
• A gym or an exercise yard, a fenced, usually open-air-area which prisoners may use for recreational and exercise purposes
• A healthcare facility or hospital
• A segregation unit (also called a 'block' or 'isolation cell'), used to separate unruly, dangerous, or vulnerable prisoners from the general population, also sometimes used as punishment.
A section of vulnerable prisoners (VPs), or protective Custody (PC) units, used to accommodate prisoners classified as vulnerable, such as sex offenders, former police officers, informants, and those that have gotten into debt or trouble with other prisonersA section of safe cells, used to keep prisoners under constant visual observation, for example when considered at risk of suicide
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• A visiting area, where prisoners may be allowed restricted contact with relatives, friends, lawyers, or other people
• A death row in some prisons, a section for criminals awaiting execution
• A staff accommodation area, where staff and guards live in the prison, typical of historical prisons
• A service/facilities area housing support facilities like kitchens
• Industrial or agricultural plants operated with convict labor
• A recreational area containing a TV and pool table
• Increasingly prisons enforce a ban on tobacco smoking

• Prisons are normally surrounded by fencing, walls, earthworks, geographical features, or other barriers to prevent escape. Multiple barriers, concertina wire, electrified fencing, secured and defensible main gates, armed guard towers, lighting, motion sensors, dogs, and roving patrols may all also be present depending on the level of security. Remotely controlled doors, CCTV monitoring, alarms, cages, restraints, nonlethal and lethal weapons, riot-control gear and physical segregation of units and prisoners may all also be present within a prison to monitor and control the movement and activity of prisoners within the facility.

  Modern prison designs have sought to increasingly restrict and control the movement of prisoners throughout the facility while permitting a maximal degree of direct monitoring by a smaller corrections staff. As compared to traditional large landing-cellblock designs which were inherited from the 19th century and which permitted only intermittent observation of prisoners, many newer prisons are designed in a decentralized "podular" layout. Smaller, separate and self-contained housing units known as "pods" or "modules" are designed to hold between sixteen and fifty prisoners each, and are arranged around exercise yards or support facilities in a decentralized "campus" pattern. A small number of corrections officers, sometimes a single officer, is assigned to supervise each pod. The pods contain tiers of cells arranged around a central control station or desk from which a single officer can monitor all of the cells and the entire pod, control cell doors, and communicate with the rest of the prison. Pods may be designed for high-security "indirect-supervision", in which officers in segregated and sealed control booths monitor smaller numbers of prisoners confined to their cells. An alternative is "direct-supervision", in which officers work within the pod and directly interact with and supervise prisoners, who may spend the day outside their cells in a central "dayroom" on the floor of the pod. Movement in or out of the pod to and from exercise yards, work assignments or medical appointments can be restricted to individual pods at designated times, and is generally centrally controlled. Goods and services, such as meals, laundry, commissary, educational materials, religious services and medical care can increasingly be brought to individual pods or cells as well.

  Conversely, despite these design innovations, overcrowding at many prisons, particularly in the U.S., has resulted in a contrary trend, as many prisons are forced to house large numbers of prisoners, often hundreds at a time, in gymnasiums or other large buildings that have been converted into massive open dormitories.

  Lower-security prisons are often designed with less restrictive features, confining prisoners at night in smaller locked dormitories or even cottage or cabin-like housing while permitting them freer movement around the grounds to work or activities during the day.