The large datacenter, which typically contains one or more mainframes and is often constructed with windows to the inside. Glass houses may contain raised floors for underground wiring and are generally very well air conditioned.
The Big Glass House
Mainframes have typically resided in the "glass house" due to stringent air conditioning requirements. Although newer machines dissipate less heat than older models, many units in one room still require substantial cooling. (Image courtesy of International Business Machines Corporation. Unauthorized use not permitted.)
The Little Glass House
Microprocessor-based computers are widely used as network servers. They are often housed in data cabinets with glass doors such as this one from AMCO Engineering. (Image courtesy of AMCO Engineering Company.)