While they can build offices in almost any location and in almost any building, some modern requirements for offices make this more difficult. These requirements can be both legal (e.g. light levels must be sufficient) or technical (e.g. requirements for computer networking). Alongside, other requirements such as security and flexibility of layout, has led to the creation of special buildings which are dedicated only or primarily for use as offices. An office building, also known as an office block or business center, is a commercial building which contains spaces mainly designed to be used for offices.