City history
From ancient Byzantium and Roman zero markers to Ottoman prayer lodges and modern UTC+3 time, Istanbul has calculated time across two continents for thousands of years.
Chapter one
Earliest documented name
"Uncertain; traditional legend attributes it to King Byzas of Megara"
Founded around 667 BC by Greek colonists from Megara on a strategic peninsula along the Bosphorus, Byzantion is the earliest well-documented urban name for the settlement, later Latinized as Byzantium.
Uncertain; traditionally named after legendary founder Byzas of Megara
Established as a Megarian Greek colony on Sarayburnu around 667 BC, Byzantion was later Latinized as Byzantium following Roman expansion.
Named in honor of Antoninus (Caracalla)
Bestowed by Roman Emperor Septimius Severus following his rebuild of the city after a siege, honoring his son Antoninus.
New Rome / City of Constantine
Dedicated as the new capital of the Roman Empire by Emperor Constantine I in 330 AD. The Ottoman Empire officially rendered the city as Kostantiniyye in formal state documents.
Derived from the colloquial Greek phrase eis ten polin ('to the city')
Derived from the colloquial Greek phrase eis ten polin, meaning to the city, Istanbul was used informally for centuries before being designated as the official international name in 1930.
Chapter two
The Ottoman Empire officially adopted standardized Eastern European Time (EET, UTC+2) for imperial telegraph and railway networks, replacing local solar time standards across Istanbul.
During World War I, the Ottoman government implemented its first experimental daylight saving time shift, advancing clocks by one hour to conserve fuel.
Law No. 697 replaced the traditional Ottoman alla turca system, which calculated hours starting from sunset, with standardized 24-hour equal hours starting at midnight.
Turkey established a recurring annual daylight saving time schedule, moving clocks forward in spring and back in autumn in coordination with European practices.
The Turkish government abolished seasonal clock changes, permanently fixing Turkey Time (TRT) at UTC+3 year-round across Istanbul and the entire nation.
Chapter three
Emperor Constantine I erected the Milion tetrapylon near Hagia Sophia, serving as kilometer zero for measuring road distances and geographic travel across the Eastern Roman Empire.
Sultan Mehmed II established Istanbul's first muvakkithane (timekeeping lodge) at the Fatih Mosque under astronomer Ali Kuscu, using astrolabes and sundials to regulate daily prayer schedules.
Polymath Takiyuddin Rasid established an observatory in Istanbul and designed advanced mechanical clocks for astronomical observation prior to the site's demolition in 1580.
The Imperial Observatory (Rasathane-i Amire) was founded in Istanbul to manage telegraphic weather data and deliver authoritative time signals for the capital.
Sultan Abdulhamid II commissioned the four-story neo-baroque clock tower beside Dolmabahce Palace, featuring imported French movements to display public time along the Bosphorus.
Astronomer Fatin Gokmen re-established the observatory at Icadiye Hill in Kandilli, establishing Turkey's central station for precise astronomical timekeeping, geophysics, and calendar calculation.