 Summer Hill 's largest mansion , Carleton ( now the Grosvenor Hospital 's main building ) , was built in the early 1880s on Liverpool Road for Charles Carleton <unk> . The suburb boomed with the opening of the railway station in 1879 , and was followed by subdivision of much of the surrounding area . Between 1880 and 1910 , the area became an upper @-@ class suburb , and was a popular choice for professionals in banking and insurance who worked in the city . Subdivision of gardens for housing continued in the 1920s and 1930s , and socioeconomically the suburb changed as some of the wealthier inhabitants moved to the North Shore . Demolition of most of the surviving mansions in the 1970s allowed erection of home units , especially within walking distance of the railway station . 
