Preservation of historical buildings is an important issue to save our cultural heritage is both a record of life and history .In recent years the Turkish government starts urban transformation projects that include renewal and restoration of some historical buildings belongs to the Ottoman period.  This paper present the details of a restoration project of a historical building in Istanbul. The selected restoration and strengthening technique aims to save the original architectural fabric of the building that has been changed among the last decades. The building is used as a chest diseases clinic in Istanbul University hospital. The building was built at the late-Ottoman period and composed of four building blocks. The structural system of the buildings is mainly unreinforced masonry URM walls. Seismic performance analysis results of the building before and after the proposed restoration scheme indicate that the resorted building is able to withstand future earthquakes safely.