The growing complexity of managing the sustainable development of cities stresses the need for interdisciplinary approaches, with a stronger articulation between different fields. The integration between heritage conservation and spatial planning has already been addressed in recent literature, ranging from a traditional sectorial perspective towards more cooperative and coordinated initiatives, occasionally resulting in integrated policies. Nevertheless, the lack of institutional and policy articulation remains among the most frequent critical governance issues unsolved. This paper unveils the integration degrees between heritage conservation and spatial planning policies in Amsterdam (The Netherlands) and Ballarat (Australia), acknowledged for local and upper governmental initiatives, such as the Belvedere Memorandum and the Imagine Ballarat project, placing both at the forefront of the roadmap to this policy integration. In-depth semi-structured interviews with municipal officials in both cities reveal that, while policy integration is aimed at, implementation remains challenging. Both cities’ heritage conservation and spatial planning fields keep operating in parallel, often in conflict, and with different perspectives on the cultural heritage commonly managed. By identifying local technicians’ challenges, this research demonstrates that policy integration between heritage conservation and spatial planning is an ongoing process that demands more effective articulation towards more sustainable and resilient cities.