The main objective of the research consists of quantifying the degree of sustainability of the city of Cáceres in terms of the inhabitant’s accessibility to public services through the use of GIS tools and urban indicators, taking into account two areas of study: The Historic Centre (PCH) and the city as a whole. The methodology applied is based on the criteria proposed by the Spanish Government derived from the Spanish Strategy for Urban and Local Sustainability (EESUL), which suggests suitable indicators for analysing urban environments. The degree of sustainability of the study areas, applied to the field of mobility and accessibility to public services, is evaluated through numerical calculations complementing the study with accessibility maps obtained using Geographic Information Systems (GIS) tools. The results show that the city of Cáceres is sustainable in terms of accessibility to bus stops, organic waste containers, household waste recycling centre, schools and education, health centres, and public administration. However, bike parking coverage and lanes, clothes and oil collection, and sports centres need to be further enhanced. In conclusion, there is little disparity in the results between the PCH and the city as a whole, not influenced by the fact that one of the areas is a consolidated historic area. This research has allowed some gaps in the topic to be addressed. However, the main limitation of this methodology consists in the need to have a considerable amount of initial starting data to be able to carry out the research. Finally, the sustainability analysis using urban indicators is considered a valuable source of information for the local manager, becoming a real planning tool in medium-sized cities.