In the 1860s the Royal Commission on the Defences of the United Kingdom recommended that a line of forts be built along Portsdown Hill. The western end of this line was Fort Wallington. Building of the fort was started in 1861 and completed in 1874. Following its sale to Mr J. Sullivan of the Southern Counties Trading Company the fort has been used as an industrial depot, and much of the old fort has been demolished - little now remains. What remains is now a Grade II Listed Building.