Istanbul is the largest city in Turkey, located between the Sea of Marmara and the Black Sea. It has a population of over 15 million people and was historically known as Byzantium and Constantinople. Santa Sofia was originally built as an Orthodox cathedral in 360 AD and later served as a mosque and now operates as a museum. Heybeliada is the second largest island near Istanbul, with a population that increases from 3,000 in winter to 10,000 in summer, and transportation is limited to walking, bicycles, or horse-drawn carriages since motor vehicles are banned.

1. ESTAMBUL
(TURKEY)

2. Istanbul, historically known as Byzantium and, later, Constantinople, is the most
populated city in Turkey and the historical, cultural and economic center of the
country.
Surface: 1,539 km².
Zip code: 34000 and 34990.
Population: 15.03 million.
Istanbul is situated at the Bosphorus – one of the world's busiest waterways – in
northwestern Turkey, between the Sea of Marmara and the Black Sea. Its
commercial and historical center lies in Europe, while a third of its population
lives on the Asian side.

3. Santa Sofia:
From the date of its dedication in the year 360 and until 1453 it served as the Byzantine
Orthodox cathedral of the Eastern rite of Constantinople, except in the parenthesis between
1204 and 1261 when it was converted into a Catholic cathedral of Latin rite, during the Latin
patriarchate of Constantinople of the Latin Empire, founded by the Crusaders. After the
Conquest of Constantinople by the Ottoman Empire, the building was transformed into a
mosque, maintaining this function from May 29, 1453 to 1931, when it was secularized. On
February 1, 1935, it was inaugurated as a museum.

4. Heybeliada
Heybeliada is the second largest island of the Prince Islands, located on the Sea of ​​Marmara. It is a
district of the Adalar district in Istanbul, Turkey.
Demography
The population in winter is about 3,000 people, although in summer the owners of the summer houses
return and the population increases to 10,000.
Transport
To avoid contamination, the circulation of motorized vehicles is not allowed, so visitors can travel on foot,
by bicycle or in horse-drawn carriages. There is no airport, so the only form of access is by boat.