Historical masonry quay walls in the inner city of Amsterdam need maintenance due to aging, and deterioration of foundations. These structures are not only critical to the transport infrastructure of the city, but also hold great heritage and monumental value being UNESCO World Heritage site. However, there is a notable lack of knowledge and documentation regarding the mechanical properties of these multi-wythe, unreinforced brick masonry walls, which poses challenges to the assessment of their structural safety. This research investigates the mechanical properties of masonry for typical quay walls presenting the results of experiments for four different quay wall locations in Amsterdam. Masonry properties were determined via core testing due to its minimal invasiveness to the structure and its ability to adopt standard extraction and testing facilities. Companion tests on brick and mortar were performed to evaluate their compressive properties. Samples were obtained from both above and below the waterline to assess the effect of submersion on the mechanical properties. This study offers an insight into the mechanical properties of quay walls in Amsterdam, enhancing understanding of multi-wythe masonry and supporting the assessment and preservation of urban infrastructure in Dutch cities.