Some aspects of the revitalization of the 14th century historical building are presented in the paper. The building was originally used as a poorhouse and a hospital for children. The original Gothic masonry building on the site was a two-storey building with a cellar, situated in a corner of two streets. In the middle of the 19th century the building was converted into a school and then the first large-scale demolition of the hospital’s Gothic walls took place. After the 2nd World War a school was also situated in the building, where it existed until the late nineties. The aim of the renovation process was to convert it into an exclusive office block. The design works were preceded by historical research and on-site investigations. Complex conversion of the object consisted in the reconstruction of the old building structure, creating the inner courtyard and covering it with a glass roof. In the existing part of the basement one of the longest single-nave vaults in Poland and the exquisite roof truss system with a lying bidding-rafter post deserved special attention during the renovation.