Dorman Long & Co. engineers. The surviving interior and exterior detailing of the 1884 platform buildings and awnings is considered rare on the Illawarra line, with other examples at St. Peters, Tempe and Rockdale. Sydenham railway station was listed on the New South Wales State Heritage Register on 2 April 1999 having satisfied the following criteria. The place is important in demonstrating the course, or pattern, of cultural or natural history in New South Wales. Sydenham Railway Station is of historical significance as a major junction station developed from 1884 to the present. Sydenham Railway Station is of historical significance as a station which demonstrates its development over time, retaining two 1884 platform buildings, along with a 1914 overhead footbridge structure and stairs, 1925 and 1962 platform buildings. The development of the station over time has included the adaptation of wayside buildings for island use. The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales. The Sydenham Railway Station platform buildings are of aesthetic significance as fine examples of railway platform building designs from 1884 to 1962, and the platform building awnings demonstrate the range of awnings used on railway buildings from the small original awning of two bays on the No 2/3 Platform building (the original minor platform) to the addition of cantilevered awnings on the rear of the buildings. The 1884 platform buildings are of aesthetic significance as good representative examples of their type and the later island platforms illustrates the contrast in styles and philosophy between the different periods of construction. The 1914 footbridge structure and stairs are of aesthetic significance as a representative haunched beam footbridge manufactured by Dorman Long & Co engineers. The place has strong or special association with a particular community or cultural group in New South Wales for social, cultural or spiritual reasons. The place has the potential to contribute to the local community's sense of place, and can provide a connection to the local community's past. The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales. The station as a whole is rare, retaining structures from the first period of construction of the Illawarra line up to the 1960s. The Platform 2/3 building at Sydenham is rare, as only five stations on the Illawarra line retain an 1880s 3rd Class platform building