It was declared a National Monument under old NMC legislation on 2 October 1981. The Wynberg Railway Company was established in 1861 to build a railway line from Salt River Junction to Wynberg, which opened on 19 December 1864. In 1876 the company was taken over by the Cape Government Railways, and the line, which had originally been built to the Standard gauge, was rebuilt to Cape gauge. The extension to Muizenberg opened on 15 December 1882, and a further extension to Kalk Bay on 5 May 1883. The final extension, to the Naval Base at Simon's Town, opened on 1 December 1890. The line was Electrified with overhead Catenary in 1928.
https://en.wikipedia.org/wiki/Southern_Line_(Cape_Town)#History
"South Africa commemorates 150 years of rail". Heritage Railway Association of Southern Africa. October 2009. Retrieved 25 July 2010.