“In 1931, replacing a small building of the same name, architects Emley and Williamson used modern materials and Art Deco motifs for a new “Castle” in Eloff Street, which was then the city’s most fashionable shopping street. Pre-cast concrete blocks provide a sense of strength and endurance; the central attic tower hints at a stronghold of the fortress, the keep. The flagpole right at the top which made it the tallest building in Johannesburg at the time enhances the notion of a citadel with pennant flying aloft.” - Blue Plaques South Africa.

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According to an article by Thomas Thale, entitled “Castle mansions shines again” dated February 19, 2004, Castle Mansions was bought by Property investment Group AFHCO Group Holdings and converted into 135 apartment comprising of 99 two bedroom flats, 14 bachelor units and 14 one bedroom and five 3 bedroom penthouse units.  However, the penthouse units were converted into smaller one bedroom and bachelor units. According to Thale, Castle mansions was the tallest building and most modern building in South Africa when it was built in 1931.

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Clive Chipkin writes: “Its pre0-eminence in the Johannesburg skyline was not based on its mandatory 10 Storey elevation but on  the height of its central Art Deco flag mast.  It was regarded as the most modern building of its day, noted for its modern plate glass shop-fronts, with Art deco brass trim and modernistic illuminated shop signage, its first floor plate glass showroom windows and its dramatically modern entrance with sans serif name letters.” Before the AFHCO renovation, the building was deserted, except for its ground floor. In this existing mixed use building there is an interaction with the street through refurbished retail. The project involves the notarial tie of two buildings on Kerk and Bree street covering most of the street block. The buildings were tied by a new bridge connecting the 197 living units of which three levels consist of new units and the other floors refurbished units.