<p>Various pieces of literature affirm that historic buildings of different grades need specific interior design strategies to maintain their historical authenticity and convey their living heritage. This study investigates three historic buildings with different historical significance: Old Boma (Grade A), Old Post Office (Grade B), and Poa Poa Restaurant (Grade C). Archival research, field observations, interviews, surveys, and comparative analysis were used as the methodology. The following were the findings: there was a mismatch between the historical building category and the applied interior design strategies, which led to some buildings losing their historical authenticity; however, the newly evolved interior spaces have enhanced a higher quality of living heritage in terms of providing communal spaces, cultural exhibition activities, community engagement, and interactions through educational and economic activities. Predicaments include lack of funding for sustaining living heritage, failure to balance historical authenticity with modernity, lack of comprehensive planning for interior adaptive reuse projects, lack of conservation skills among the stakeholders, and a limited legislative framework for conserving buildings. The study recommends the following: fostering collaboration among various stakeholders (building owners, government, municipalities, local communities, and investors) to minimize conflicts and promote holistic adaptive reuse of historic buildings.</p>