The diploma defines three areas - A, B and C - of archaeological sensitivity, which takes into consideration the property location and its surroundings, with an emphasis on its relationship with the environment. Since 1963 the Military Museum has been classified as a property of public interest.

The three distinct areas of special protection represent different types of works and previous actions to these which should be carried out. According to the decree-law the “diploma defines a special protection zone that takes into account the location and surroundings of the property, namely its relationship with the landscape, the consolidated urban fabric and other properties with heritage and/or urban planning relevance.”

Therefore, in zone A, an archaeological intervention needs to take place before the works start, in order to promote its preservation. In zone B, which relates to the urban interventions to be carried out, a prior archaeological excavation must take place so that the interventions’ viability can be checked. At last, zone C, defines the area which requires permanent archaeological monitoring.

The General Directorate of Cultural Heritage, in collaboration with the Lisbon City Council, suggested the limits intended to safeguard the surrounding area of the listed property, and the National Council of Culture gave its approval.