Özet:

It is an important ancient city with its multi-layer cultural heritage dating to the Roman, Byzantine, Selchuklu and Ottoman periods. During the Roman Peace Period (27–180 BC), when the city of İznik did not need the defense system, the monumental doors symbolizing the entrance to the city were built in the future to the end of the main road axes of the city (MS 78–79). But after the Gothic attacks in the 250s, the walls were needed in the periods of Gallienus (253-268) and Gothicus (268-269). In the late period, Lascaris (1205-1222), Vatatzes (1222-1254) made significant interventions to protect the city by building external walls outside of the main walls. In 1330 Isnik was conquered by the Turkish Sultan Orhan. The Nikaia defense system consists of the main walls, the later added external walls, doors, bridges, and the outer circuits. The main walls, which are the first stage of the defense system, have gained the character of the internal wall after the exterior walls are built, and are the subject of this research. These walls, as they see interventions such as repair, rebuilding in the historical process, reflect the traces of different periods. The main wall system, which is about 5 km long, has seen interventions such as repairs, reconstruction, expansion, strengthening during the historic process, but when architecture is studied, it is clear that the structure still retains its monumental character. The construction materials and systems used in the construction of walls and walls differ according to the construction period. In the framework of the research, the general architectural characteristics of the monumental doors, wall walls and walls located in the walls built as the main wall/internal wall of the İznik walls are described. Furthermore, the details identified that the construction system and the use of materials differed during the inspections on the site, the researchers are intended to share the data obtained and produced in the research.

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