Marmara Island is the largest of the large and small land masses scattered around Kapıdağ. The island has five villages, all of which are on the seashore. The Marmara district center is located in the south of the island, leaning back against steep cliffs. The northern half of the island is made of marble, while the southern half is made of granite. The first name of the island was Elafonesos (Deer Island). It was later named "Prokonnessos". The Palaces, located behind a small harbor on the northeastern shore of Marmara Island, were named "Palatia" because of the building known as "Justinian's Palace" where the officer responsible for the marble production in the quarries located on behalf of the emperor in ancient times lived. Prokonnessos, a colony of Miletus in the 8th century BC, has been famous for its marble for centuries. Especially during the Roman Empire, the quarries, where marble production was quite intense, produced works of architecture and sculpture and shipped them to the coasts of Anatolia, the Adriatic, the Mediterranean and the Black Sea. Thus, Prokonnesos played an important role in meeting the marble needs of the Roman Empire. The Palaces Open Air Museum contains large-scale marble works, most of which are semi-finished and allow the stages of marble processing to be followed. Small-sized works are kept in the storage room on the upper floor of the town hall.

Turkish Museums – Palaces Archaeological Site