Cultural assets are referred as the sum of the economic, social and cultural history of a civilization. For this reason, restoration, preservation and all kinds of interventions for this valuable heritage are of great importance. Reusing historical buildings according to the needs of the day is among the ongoing discussions in the field of architectural preservation and restoration. This study aims to determine the typology of the historical identity of a historical building, which is shaped by the demographical properties of the region and which reveals an important cultural value today, after its transformation over the years as a result of reusing. Examining the Levantine structures in Mersin, which have an important cultural heritage, is important in terms of revealing the historical values of the region. Mersin, located in the Mediterranean region of Türkiye, is one of the most important port cities of the country. This situation has caused the demographic to differ in the city and various historical buildings such as churches, monasteries, mosques, kulliyes, traditional houses were designed in different styles. There are many studies investigating these structures in the literature, but there is no current study on the Levantine building that emerged as a result of the different demographical properties in Mersin. In this study, the Old Üç Ocak Primary School, which is a Mersin Levantine building, was discussed and it was aimed to fill this gap in the literature and to make a documentation study of the structure. In the study, the Latin-Italian Catholic (Cathedral) Church Complex is included, together with the general consideration of the Levantine buildings in Mersin. The Old 3 Ocak Primary School, which is located in the complex and whose restoration process continues today, has been examined. In line with the determined goals, first of all, the important processes in the transformation of the historical school were determined in the light of the existing studies in the literature and documents in local institutions, together with on-site observations. The determined information is discussed under three headings as plan, facade and material and technical features. The remarkable architectural values that the building contains and revealed, together with the cultural and architectural features of the period in which it was built, are evaluated. Within the scope of the evaluations, it has been seen that the examined Old 3 Ocak Primary School building has similarities with the traditional Mersin and Levantine buildings. It has been concluded that the different building types formed by the effect of the demographical properties may show typological similarities with the structures formed by the same demographical properties in a different region and with the existing traditional buildings in the region. Since the preparation of the survey and restitution projects and the restoration of the building will not be sufficient alone for the preservation of historical buildings and cultural heritage, it will provide more effective preservation, as in the Old Üç Ocak Primary School, where its sustainable preservation is addressed with the proper reusing and continuous use of a historical building. With this study, it is aimed to draw attention to the documentation and preservation of Mersin Levantines, which have a high original value.