Masonry chimneys were key elements of post-industrial factory buildings. Built on a large scale in Portugal from the nineteenth century, factory buildings have been in use until the beginning of the twentieth century, afterwards being progressively abandoned, transformed or demolished. During this degradation process, the industrial chimneys are often separated from other structures and become isolated elements, i.e. sculptures to the memory of the site's past activity. Moreover, although most of these industries and chimneys were located outside ordinary living areas, they are actually surrounded by dwellings or placed inside leisure areas. This new framework demands safety evaluations of the chimneys, which involve preliminary on-site surveys. This work shows the analysis of the geometric and material data from on-site surveys and dynamic identification procedures carried out on 10 industrial brick masonry chimneys. In particular, it establishes correlations between the chimneys geometrical and mechanical characteristics and proposes simple procedures to help designers to assess the safety conditions of these chimneys and evaluate eventual reinforcement needs. This article is part of the theme issue 'Environmental loading of heritage structures'.