This set of detail survey maps of Sydney in the inter-war period was prepared by the Fire Underwriters’ Association of NSW. The maps were originally produced in 1916, reprinted and extended on 1 August 1925, revised and reprinted in April 1933, and revised in July 1940. Their purpose was to record the locations and plan view of properties, together with the building materials, associated fire risks, and fire precautions. This information could then be used to assess the level of risk for a building to be insured. The maps cover the commercial heart of the City, from Circular Quay to Haymarket, and from Darling Harbour to Elizabeth Street. Additional areas included are: parts of East Sydney; blocks around Bay St Ultimo; and some high-risk industrial sites on Blackwattle Bay. The scale of the plans is 40 feet to the inch (1:480) except for the original key map which is 528 feet to the inch (1:6336). The key map includes an explanatory legend for the colours and symbols used in the maps. The maps are extensively annotated to show the names of firms occupying buildings, the businesses they conducted, and details such as positioning of stairways and street addresses. When a building was demolished, or a new building constructed, or significant changes made, amendments to the relevant map sheet were issued by the Fire Underwriters’ Association. These were intended to be cut to shape and pasted over the obsolete section of the map, to bring it up to date. Many of the original sheets in the City of Sydney Archives have these pasted updates added.