Thirteen (originally twelve) storey office block at King and Castlereagh Streets designed in 1911 by architectural firm Spain, Cosh and Minnett for the estate of the late Sarah Jane Marks, who had died in 1909. The building was named after her family's property Culwulla at Jamberoo as a memorial to her from her sons Dr Herbert J W Marks and Walter Moffitt Marks. At 50 metres high, it was the tallest building in Sydney and fears were raised that Sydney would develop a New York style skyline with darkened streets. It was also considered a fire hazard as existing equipment was incapable of reaching this height. The city's building regulations were subsequently amended with the introduction of the 1912 Height of Buildings Act by the New South Wales government, restricting building heights to 45 metres. This remained in force until 1957.