Cultural heritage is recognized as a driver and enabler for sustainable development, and its role within the circular economy and circular cities is gaining attention. Its adaptive reuse plays a significant role in this while prolonging the heritage lifespan, preserving the values associated with heritage assets, and creating shared values. The adoption and implementation of the adaptive reuse of cultural heritage practices present challenges at multiple levels. This research aims to identify these challenges and propose solutions to overcome them, considering the post-industrial port city of Rijeka, Croatia, as a case study. The adaptive reuse of cultural heritage practices was assessed through a stakeholder engagement workshop performing a multi-scale analysis using the Historic Urban Landscape approach as an assessment framework. Forty-nine themes were identified by content analysis of the challenges and solutions identified by stakeholders involved in adaptive reuse practices and decision-making in the city. The five most mentioned themes refer to aspects relating to participation, capacity, regulatory systems, economics-finance, and knowledge. These findings provide evidence of challenges for policy- and decision-makers to be addressed in policy-making. Solutions are also suggested to facilitate the adaptive reuse of cultural heritage in the city of Rijeka and similar contexts, such as introducing policies to support participatory decision-making whose absence is a barrier.