The paper exemplifies the application of the methodology involving historic and architectural research complemented by HBIM and operational modal testing in the structural modelling of a heritage palace, the Galleria degli Antichi in the historic town of Sabbioneta (Italy), included in the UNESCO World Heritage list since 2008. This monumental building was built in the 16th century. Full details on the history of the building and the information obtained in the nondestructive survey are given in the paper. The good knowledge of the structural geometry, along with the complete inspection carried out and the large number of identified vibration modes, allowed to establish a numerical model of the monumental building for a first quantitative a...