The seismic retrofitting of listed buildings presents a complex challenge, as it requires the integration of structural safety measures with the goals of monument conservation. These challenges are amplified in historic urban environments, where buildings are often interconnected and exhibit heterogeneous construction styles. Standard planning processes may not be fully applicable in such cases, requiring customized solutions. This paper focuses on a listed corner house with low storey heights in an old town setting in the city of Zug. The property is a heterogeneous structure. The origins of the building date back 500 years, and it has undergone numerous modifications throughout its history. Due to significant structural disrepair, gradual removal of fixtures and panelling was necessary to expose the load-bearing structure. The condition and the historic value of the structural elements were evaluated through collaboration between the disciplines of architecture, civil engineering, and heritage conservation to develop a comprehensive understanding of the possible options. Once the assessment was complete, work began on the floor plans and concepts for the structural retrofitting measures. The assessment and the measures implemented are described in this paper. The approach of exposing the structure before designing the retrofitting measures allowed for minimal intervention, but extended the building's period of disuse, which required clear communication and understanding from the client. This paper highlights the interdisciplinary process and the need for tailored solutions in the seismic retrofitting of historic buildings, offering insights into the legal, technical, and conservation-related challenges.