Abstract: A public building alarm system for displaying information relating to potential alarm conditions within or about a public building area, employs an alarm condition display screen for informing a fireman, for example, of the nature and location of a possible fire. For the vast majority of the time, in the absence of an alarm condition, display control circuitry causes the alarm display screen to display information of general interest to the public, in high traffic areas of the building frequented by persons visiting the building. This is in contrast with alarm conditions of no interest to the general public. Such information can include advertising, enabling the building owner to collect advertising revenues to help offset the cost of the alarm system. Upon the occurrence of an alarm condition, the alarm condition display is immediately substituted for the information of general interest display.