City One is a large housing estate in Sha Tin. There are 52 blocks in total providing 10,642 units. Each block is with 30 storeys high and with flats ranging from 389 sq. ft to 1,018 sq. ft. The development phase was divided into seven stages, participated by four major developers in Hong Kong from 1981 to 1988. Concerning the demography, the population is around 25,000, among which 42% achieve university attainment.
City One is within the vicinity of City One MTR station, facing Shing Mun river, surrounded with other residential and recreational buildings. A highway namely Sha Tin Road is also close to some blocks.