Around the world, there are several names for buildings that perform the same function: Hotel-de-Ville in France, Palazzo della Comunitá in Italy, Cabildos in Spain, Paços do Concelho in Portugal, and Casa de Câmara e Cadeia (literally House of Chamber and Jail) in Brazil. This article discusses the restoration and reuse of Brazil’s oldest building of this style: the House of Chamber and Jail in Mariana, a city in the state of Minas Gerais, built in colonial times. Following the Portuguese Crown standard construction codes, this colonial building was designed in 1762 by architect José Pereira dos Santos and its construction was carried out by José Pereira Arouca. Both came from the district of Porto, Portugal. As a public building, it had two floors: the Chamber, which operated on the second floor and served as the City Council, and a regular jail that occupied the first floor. This article analyses the results of the interventions that took place over the years, examines the suitability of original building materials and systems with those used in these interventions, highlights the importance of the building, the heritage designation process, the surrounding environment and ultimately, the physical, functional, and visual relationships of the building with the city. As for the recent restoration intervention carried out, in 2021, by the authors of this article, it examines the causes of the building’s deterioration, diagnosis, state of conservation, restoration project and methodology. All the undertaken interventions are analysed in light of modern principles of cultural heritage preservation.