İznik enjoyed a period of expansion and prosperity under Roman rule. The first phase of today’s city walls was built in the late Roman period probably against the attacks Goths began in 258 AD. The four monumental entrance gates of the city, which were called Lefke (east), İstanbul (north), Göl (west) and Yenisehir (south) were built by the Roman Emperors Vespasianus and his son Titus. The other buildings dated to the Roman period are the theatre located on the southern west part of the city and the Obelisk of Gaius Cassius Philiscus erected on the road from İznik to İzmit (Nicomedia).
During the Byzantine period, İznik became an important religious centre, particularly after the Emperor Constantine was converted into Christianity in 313 AD. The first Christian Council called the great Council of Nicaea was held in İznik in 325 AD with the participation of bishops more than three hundreds came from different parts of the empire. The Seventh Ecumenical Council was also convened in Nicaea in 787 to deal with the iconoclastic controversy on the use of icons. This council was held in the church of Hagia Sophia, constructed by the Emperor Justinian over the ruins of the former church dating back to the 4th century. As it was demolished after an earthquake in the 11th century, the church was rebuilt as a basilica with three naves. The church is still located at the point where the roads leading to the four main gates in the district centre meet. A hypogeum, an underground grave found in the rural part of the town is one of the oldest Christian structures in İznik built in the 4th or 5th centuries AD. Covered by a vault and decorated its ceiling and with colourful frescoes, it is one of the rare examples of the period of early Christianity. Built as a part of the Hyakinthos Monastery in the 7th century, the Koimesis Church was also one of the most important early Byzantine architecture. The church was destroyed in the 1065 earthquake. Although it was repaired in later times, only some of its ruins have survived to the present. Böcek Ayasması (Baptistery), a round structure with a water spring at the center of a quadrangular fountain, is also erected as part of the Hyakinthos Monastery.
Anatolian Seljuks took over Nicaea in 1081, made the city their capital and renamed it İznik. The city was regained by the Byzantines in 1097. During this period, some other churches were built such as Hagios Tryphonos Church with a cross-shaped plan. After the Fourth Crusade captured Byzantine capital of Constantinople in 1204, İznik became the core of the successor Byzantine Empire after emperor Theodore Laskaris founded the Empire of Nicaea there. During this period, the city became an important political and cultural centre with the construction of imperial and civic buildings such as the palace of the Patriarch, the hospitals, the charity institutions, and the churches. The city walls were also expanded and reinforced with plenty of towers.
When Ottoman Beylik captured İznik in 1331, they also formed their capital here. Although İznik enjoyed this title for only short period, it was during this period that Ottomans built fine examples of early Ottoman architecture, such as the Haci Özbek Mosque (1333), the Green Mosque (1378–91) also known as the Yesil Cami, the Yakub Çelebi Mosque, Mahmud Çelebi Mosque, Nilüfer Hatun İmareti (Soup Kitchen) (1388) and the Süleyman Pasa Madrasa (mid-14th century). During this period, Ottomans also used existing buildings for their own purposes. For example, the Hagia Sophia Church was converted into mosque called Orhan Camii. During the reign of Sultan Süleyman the Magnificent, a minaret was erected and its walls were decorated by the famous architect Sinan.
With the growth of İstanbul as an Ottoman political and cultural centre after 1453, İznik lost its prosperity. The city was revived soon, however, with the introduction of faience pottery making. During the 16th and 17th centuries, İznik became famous for its beautiful tiles which decorate mosques and palaces throughout the Ottoman Empire. Archaeological excavations carried out in tile kiln sites for more than thirty years by the Istanbul University Department of History of Art has not only revealed the unique production and decoration techniques of İznik ceramic, but also shed some light on the social and economic development of the region. The tile kiln excavations at İznik are still going on today.
Justification of Outstanding Universal Value
Situated in a fertile valley nearby the lake with the same name, İznik is a small historic town still enclosed within its ancient walls surrounded by a beautiful landscape. The historic urban layout of the town is still visible with its grid settlement plan remained since the Hellenistic Period and monumental structures from the Roman, Byzantine and Ottoman periods. The city walls which 4970 m in length, which was built in the late Roman period, then expanded and strengthened during the Byzantine and Ottoman period, is one of the distinctive features of the city. It surrounds settlements creating an irregular polygon with four monumental and several small gates. The walls were also fortified by more than a hundred towers some of which have inscriptions. In addition, columns and other architectural fragments from the ruins of more ancient edifices have been inserted into the city walls.
Served as a capital city to Seljuk, Byzantine and Ottoman states respectively, İznik bears exceptional testimony to early examples of cultural, architectural and artistic accomplishment of these cultures. It hosted the most important examples of early church in the history of Christianity. The earliest examples of mosque, madrasa and soup kitchen belonging to the Ottoman Period were all constructed in İznik. It is also a place of co-existence displaying unique synthesis of cultural, architectural and artistic creations of Byzantine and Ottoman cultures, evidence of which can be found in the form, design, material and artistic features of the buildings which were built in the transition period from the Byzantine to the Ottoman Empire.
İznik bears exceptional witness to the introduction and early expansion of Christianity. The city hosted the two of the most important ecumenical councils recognized by all churches. During the late antique and medieval period, the city was widely known not only because of its significant role during the formation and development of the faith of Christianity, but also important influences resulting from these meetings. In addition to being the first ecumenical council, the Council of Nicaea (325) resulted in the adoption of the first uniform Christian doctrine, which was called the Creed of Nicaea, still widely used in Christian liturgy by the Catholic, Orthodox and Anglican communities. The Seventh Ecumenical Council (787), on the other hand, had also significant influences especially for the depiction of sacred images representing the saints, Christ, and the Virgin as well as narrative scenes. The veneration and use of icons, which had formerly been banned during the reign of Leo III (717–741) was restored after this council. Thereafter, the icons began to be widely used in churches and monasteries all around the Byzantine Empire. Indeed, İznik still retains its spiritual value for the Christian believers.
During the Ottoman Empire, İznik gained a world-wide renown for the second time as the centre of production of ceramic tiles, one of most beautiful and enduring types of Turkish-Islamic art. The art of ceramic, the origins of which could be found in the Neolithic Site of Çatalhöyük, reached its perfection during the 16th century İznik. Although the first known ceramic production dates back to 3rd century BC China, the glazed technique was discovered by the Assyrians, developed through Central Asia and Anatolia, reached its maturity in İznik. İznik ceramics have often been depicted with floral motifs such as tulip, hyacinth, pomegranate and carnation and mostly blue, turquoise, green and red in colour. This finest works of art have still been manufacturing in İznik.
Criterion (ii): İznik has been an important centre of the production of the ceramic and exerted great influences across the regions for long centuries. At the beginning of its production, the İznik tile was mostly served to the Ottoman imperial palace in Istanbul. After it began to be exported, İznik tile ceramics created a new art movements across the regions. The technical quality and the beauty of its designs have made it one of the most popular art forms major cultural centres of the world. Today, fine examples of İznik tile can be found almost the entire world’s leading museums.
Criterion (iii): As one of the capitals of the Anatolian Seljuks and the Ottomans, İznik represents the unique testimony to cultural, architectural and artistic examples of these cultures. The Empire of Nicaea founded in İznik was the core Byzantine successor states founded by the Laskaris family after Constantinople was occupied during the Fourth Crusade. It lasted from 1204 to 1261 when the Nicaean recovery of Constantinople re-established the Byzantine Empire. Therefore, the architectural remains of İznik represent transitional periods in the history of the architecture of the Byzantine and Ottoman Empire from its earliest days. Hacı Özbek Mosque is the oldest Ottoman mosque in İznik, dating back to 1333. Süleyman Pasha Madrasa is one of the first examples of Ottoman Medreses built in İznik in the first half of the 14th century. The Green Mosque is one of the most significant mosques of the early Ottoman period. Known as the first soup kitchen built with a reverse T-shaped plan, Nilüfer Hatun Soup Kitchen is a fine example of early Ottoman architecture. Indeed, this period of building activities of İznik is also important for displaying the unique politic, economic, cultural and artistic interactions between the Byzantines and the Ottomans. Some of the buildings of early Ottoman period were constructed by re-use of construction elements from the existing Byzantine buildings. In addition, the production İznik tile was as a tangible and artistic evidence of the social, economic and cultural life of the Ottoman Empire from the fifteenth to seventeenth centuries.
Criterion (v): With its historic cultural landscape shaped over centuries, İznik represents a testimony to the human interaction with both the lake and the surrounding agricultural areas. The basin of Lake İznik has fertile agricultural lands in which olive groves, vegetables and fruits have been cultivated for centuries. The source of income created from these productive lands has played significant role not only for the selection of the site suitable for human settlement and as a capital city by different cultures, but also for the protection of its historical and natural value for centuries. The remains of the fortifications, the grid layout, and the tumuli around the city illustrate the continuity of the landscape. İznik still displays how closely the town’s inhabitants were connected with the lake and their agricultural hinterland.
Criterion (vi): İznik is directly and tangibly connected to great historical and religious events that shaped the faith of Christianity. The most two important meetings in the history of Christianity were convened in İznik. Called by the emperor Constantine the Great, the first Council of Nicaea held in 325 confirmed the divinity of Christ, as the one true God in deity with the Father, which had also been widely believed by the early Christian communities. It was also an agreement on when to celebrate Easter the most important feast of the ecclesiastical calendar. The Seventh Ecumenical Council held in 787 had also important influences. After this council, the icons were considered worthy of veneration and began to be widely used in the churches and monasteries throughout the Byzantine Empire.
İznik contains all the key attributes that convey its outstanding universal value, testifying to the urban texture and its relationship with the lake and surrounding rural areas. Its completeness is represented by the fact that the city exists today in an unchanged form. İznik is still enclosed within its ancient walls and the city still retains its grid urban plan, the two streets north/south and east/west oriented cross the town meeting at a right angle. The city walls has different construction phases dated to the seventh, tenth and twelfth centuries, evidence of which can be found in different material and building techniques. Considerable parts of the fortifications preserve features of their original form, design, materials and use, harmonized with the local terrain and their surroundings. It appears that the ancient theatre was converted into a mass graveyard in the 13th century. During the Ottoman period, there were also ceramic kilns within the ancient theatre. Its stones were used as construction materials especially in the restoration of the city walls during the Byzantine and Ottoman period.
During the Turkish war of Independence, İznik went through turbulent times. During this period, some of the buildings such as the Koimesis Church were seriously damaged. Only some of the architectural parts of this early Byzantine church have survived today. The other problem is inattentive restorations of some of the Byzantine and Ottoman buildings. Although the city has not gone through adverse effects of development or large increases in population, the physical remains are vulnerable to some natural and manmade risk factors. It needs detailed research and experimentation addressing the identification, stabilization and protection approaches. In fact, İznik still provides an important archaeological reserve area as evidenced by a very recent discovery of the remains of an ancient basilica about 20 meters from shore in Lake İznik by Uludag University Archaeology Department. Although it needs further research, the basilica is considered to have been built in memory of Saint Neophytos, who was killed during the reign of emperor Diocletianus mentioned in the written sources. It is also estimated that the basilica collapsed during an earthquake that occurred in the region in 740.
The historical, archaeological, natural sites of İznik are under protection by the Turkish Legislation for Preservation of Cultural and Natural Property, Law No.: 2863. Initially, Bursa Regional Council for Conservation of Cultural and Natural Heritage registered the site as historical urban site with the decision dated 12.10.1983 and numbered 969. This decision was revised in different time periods extending the boundary and the type of the areas to be protected by law including 1st and 3rd degree archaeological sites, as well as natural and urban sites. The conservation plan of the urban and archaeological site was approved by the Bursa Regional Council for Conservation of Cultural and Natural Heritage in 1990. There have also been some attempts to maintain the city as an important tile production centre. To this aim, İznik Tiles Atelier and the Tile and Ceramic Research Canter were opened in 1996. It is now possible to produce İznik tile almost the same quality of those of the 16th century.
Comparison with other similar properties
With its various distinctive features, İznik can be compared with several other properties in different grounds. First of all, the grid plan with its four main gates is a common feature of many ancient Greek and Roman cities such as Miletos, Priene, and Nikopolis, etc. Surrounded with city walls built in the Roman period with important extensions and restorations during the Byzantine and Ottoman periods, historic town of İznik can be compared with several other cities in Turkey such as İstanbul, Diyarbakır, Alanya, Kayseri, or in a more general comparative context, with some other fortified cities in Mediterranean and Near East such as Old town of Corfu in Greece, Verona in Italy, Dubrovnik in Croatia, Valetta in Malta, all of which were already inscribed on the World Heritage List. Unlike many of the fortified cities in Turkey, İznik stands out that the life is still enclosed within its ancient walls, united with its rural environment and the city has not gone through adverse effects of development.
Surviving historical buildings in İznik can be compared individually with other buildings particularly with İstanbul and Bursa. For example, İznik Hagia Sophia built by Justinian I in the middle of the city in the 6th century was modelled after the great Hagia Sophia in İstanbul. Buildings types dated to the early Ottoman period such as mosques, madrasas, imarets’ more elaborate versions could be found in the city of Bursa, the capital of Ottomans after İznik.
What makes İznik different from such properties is the existence of combination of political, cultural, religious and artistic features. The political importance of İznik is evinced by its selection as a capital centre for different cultures. Furthermore, it has been an important centre for the production of pottery for long periods. The types of tile and ceramic kilns consisting of an oven set above a fire chamber generally buried in the ground have been found in Kalehisar, Ahlat, Edirne, Kütahya and Diyarbakır which emulated İznik tiles.
İznik tile kilns can also be compared with the other important production centre in the world especially in China and Korea. The Yue Kiln Sites at Shanglin Lake was celadon production centre of the Tang and the Song dynasties primarily produced the best art form of China’s celadon between 8th -10th centuries. Kangjingun Kiln Sites Republic of Korea is another important example, most of the kilns date from the 11th to the 13th centuries. Both of sites were inscribed in Tentative List. From the 9th to the 16th century, works of Yue Kiln sites were exported to other countries and regions of Asia, Africa and Europe. Chinese ceramics had long been admired, collected and emulated in the Islamic world. It is also known that Chinese ceramics had significant impact on the introduction of pottery making in the Ottoman Empire and the development of İznik tile. Although Chinese ceramics had significant influences, İznik tiles developed with its distinctive production techniques, styles and decorations. İznik also differs from other properties for its strong association with important historical and religious events. In the history of Christianity, from the First Council of Nicaea (325) to the Second Council of Nicaea (787), the first seven ecumenical councils represented an attempt to reach an orthodox consensus and to establish a unified Christendom. The other councils of this first seven councils were convened in İstanbul and Ephesus. In sum, none of these areas has the same features with İznik which is a peaceful historic town located on the lake with outstanding natural beauty, having spiritual values with important archaeological and historical finds.