The complex known as Lisbon Castle and City Walls is classified as a National Monument by Decree of 16 June 1910.
The monument belongs to the Portuguese State and was given to the Lisbon Municipal Council on a provisional basis on 13 September 1934 and then permanently on 31 May 1942.
On 8 June 1979, the Reformulation of the Conditions for the Assignment of the Castelo de São Jorge was published and in October 1995 the Lisbon Municipal Assembly entrusted the Castelo de São Jorge to EBAHL (Equipamentos dos Bairros Históricos de Lisboa E.M.) which was succeeded, in 2003, by EGEAC (Empresa de Gestão de Equipamentos e Animação Cultural E.M.).
The monument consists of the Castle, the ruins of the Paço da Alcáçova (Palace of the Citadel), the Place-of-Arms, a wide panoramic viewpoint over the city, an archaeological centre, gardens and a series of walls.
The monument occupies an area of around 4 hectares and is delimited by a large ring of walls that correspond, in part, to the limits of the old Lisbon citadel.