Heybeliada is the second largest of the Princes' Islands in the MarmaraSea near Istanbul. It has a lenghth of 2.7 km from north to south and a width of 1.2 km from east to west. Heybeliada was known as “Demonisos” or “Chalki” in the past. It takes its present name of Heybeliada from the shape of a bag that it resembles when looked upon from a distance.
Heybeliada, located in the center of the Princes' Islands with three monasteries, was a traditionally fishing town until the beginning of the nineteenth century. The population of the island grew steadily from 800 to 2,000 with the introduction of steamboat services in 1846. A Greek Orthodox monastery, the main Greek Orthodox School in Turkey, the Elen Trade School, and the first private trade school in Turkey, and the Naval Cadet School (Bahriye Mektebi) have undoubtedly played an active role in stimulating the economic, social, and cultural development efforts on the island. Due to the wealthy Greek community which has built kiosks and mansions on the island as well as a high level of entertainment available, the island has reached a very high economical level. Papa Yani, the first Mayor of Heybeliada, was appointed in 1887, and a successful telegraph cable was laid to the island in the same year.
With the initiation of steamboat services to Heybeliada, Turks have also developed an intersted in visiting the island. Abbas Halim Pasha, the Governor of Egypt in the 19th century, had a kiosk, which carries his name, built on the island at that time. This caused the settlement’s kiosk circle to improve greatly over the course of time. Due to an earthquake in 1894, the island’s buildings were extremely damaged. Ambela, the name of the foremost entertainment venue of the time, was destroyed by a fire immediately after the earthquake. Like every other part of the world, during World War I, the islanders experienced a very difficult time. Moreover, the Elen Trade School was closed in 1915, and the school building was later put into service as a home for orphaned girl.
After the declaration of the Republic of Turkey in 1923, the most important advancement for the island was the opening of the Heybeliada Sanatorium,which was a glimmer of hope for those with tuberculosus. It was later closed and became a thing of the past in the memory of hundreds of people, including the famous Turkish poets, Ece Ayhan and Rifat Ilgaz in 2005. Because of security concerns, during World War II, the Naval Cadet School was moved to Mersin province located in southern Turkey on the Mediterranean coast between Antalya and Adana. After the civil servants employed at the Naval Cadet School and its students left the island, the island became desolated. After the end of World War II and when the Naval Cadet School returned to the island in 1946, the island became active again. Following the events of September 6 and 7 of 1955 in Istanbul, , a part of the Greek minority of the island immigrated to Greece and the island lost its vivacity. After the 1980s, the island, like other settlements in the city, experienced a population explosion due to immigration and a rapid non-planned urbanisation.
The highest peak of the Heybeliada is Değirmen Tepe (peak) (136 m). Taş Ocağı Tepe (128 m) is located on the eastern end of the Değirmen Tepe. The other mountains of the island are Umit Tepe (85m) on which Heybeliada Priest School is located, and Makarios Tepe (98m), Makarios Monastery, on which located on top of the island. The island hosts four harbours: Bahriye Harbour, Mendirek Harbour, Değirmenburnu Bay and Çam Harbour. Çam Harbour, called “Port Saint Maria” in old times, is the greatest harbour of the island and is worthy of being shown as a natural wonder. The Terki Dünya Monastery (meaning “Leaving the World Behind Monastery”) was originally built in the woods by Çam Harbour in 1868, but it was rebuilt from wood after an earthquake occured in 1894. Apart from that monastery, the Aya Yorgi Uçurum Monastery (1758) and the Saint Mary Church, a place of pilgrimage built by V. İoannes Palaiologos in 1341, are also situated on the island of Heybeliada. Ayia Eufemiya Ayazma (holy spring of Orthodox Greeks) is seen as a historical site of the island located southeast of the Naval Cadet School.
During the summer, Heybeliada becomes lively with its summer home vacationists and touristic visitors. Tourist activities include horse-drawn carriages and donkeys on the island. Many famous individuals enjoy visiting the island. It was of particular importance to Hüseyin Rahmi, who is a famous Turkish author who has spent most of his life time on the island. The islanders have looked after their author and have put up a statue of him in the park located in front of the island port. Additionally, the author’s house on Değirmen Tepe was turned into a museum and his name was given to the island’s high school.