Preserving historical buildings is a very essential aspect as these buildings represent sociocultural indicators of the past. Historic buildings may lose their function during their life stages and become deserted. Adaptive reuse is a way to sustain a building by changing its function according to its area needs and current context. Qishla Castle is one of Koya, Iraq’s most important historical buildings. In addition to its historical and cultural status, it has an important geographic location in the city center. This paper aims to test the potentiality of reusing this historical building. The Adaptive Reuse Potentiality ARP model was applied to the Qishla Castle in Koya. To apply this model to the Qishla area, a working paper was prepared, including a set of questions to estimate building obsolescence attributes, these questions were answered based on a survey and interviews with experts. Results obtained from experts showed that the building was constructed solidly and to a high level of quality despite its obsolescence. Building physical life is estimated at 250 years, the building age is 152 years, the useful life is estimated at 161 years, ARP value is 62.24%, that is, the Qishla building has a high potential for adaptive reuse.