Environmental factors, projected to intensify due to climate change predictions, can expedite the degradation and aging of historic building materials like masonry. Among the primary degradation risks, salt crystallization stands out. Historical masonry quay walls, a vital component of the infrastructure of numerous European cities, notably in the Netherlands, present a unique case study in this aspect. This uniqueness arises from their continuous and long-term exposure, not only to environmental influences but also to salts in the canal water. To investigate this, a coupled multiphase modeling strategy for the hygrothermal analysis of masonry structures is used to simulate the impact of salt crystallization on multi-wythe masonry quay walls in the city of Amsterdam. This modeling strategy is governed by four highly nonlinear and fully coupled differential equations addressing moisture mass conservation, salt mass conservation, energy balance, and salt crystallization/dissolution kinetics. The model has been previously validated against laboratory experiments, but it is here applied for the first time to a real case study. A parametric study adopting a 2D sectional numerical model of the quay wall was performed. Parameters investigated include the effects of boundary conditions at different faces of the quay wall, masonry bond pattern, salt concentration in the water as well as time variance of environmental relative humidity. The findings of this paper can be used to identify critical environmental conditions for quay walls as well as provide the basis for explaining the through-thickness variation of mechanical properties found in previous research.@en