Open Travel Guide
History of Istanbul

Istanbul History & Heritage Guide 2026

A historical companion to Istanbul — what happened, where to stand, and what survives.

Istanbul is Turkey's largest city and cultural capital, straddling two continents across the Bosphorus Strait. Once the capital of the Byzantine and Ottoman Empires, it's a city of stunning mosques, grand bazaars, and vibrant neighborhoods blending East and West.

Historical timeline

Key moments that shaped Istanbul.

  1. 1

    Greek Byzantium

    657 BC - 330 AD

    Founded circa 657 BC by Greek colonists from Megara led by Byzas. Strategic location controlling Bosphorus trade made it prosperous. Came under Roman control in 73 AD.

  2. 2

    Constantinople - Capital of Christendom

    330 AD - 1204 AD

    Emperor Constantine I dedicated the city as his new capital on May 11, 330 AD. Under Justinian I in the 6th century, it became the world's largest city with up to 800,000 inhabitants. Hagia Sophia was built in 537 AD.

  3. 3

    Latin Empire (Crusader Occupation)

    1204 - 1261 AD

    The Fourth Crusade sacked Constantinople in 1204, establishing the Latin Empire and looting the city. Byzantine Empire survived in exile at Nicaea until 1261.

  4. 4

    Late Byzantine Constantinople

    1261 - 1453 AD

    The restored Byzantine Empire was a shadow of its former glory, reduced to Constantinople and its immediate surroundings. The extraordinary Chora Church mosaics were created in this period.

  5. 5

    Ottoman Conquest of Constantinople

    May 29, 1453

    After a 53-day siege, 21-year-old Sultan Mehmed II breached the Theodosian Walls. The last Byzantine Emperor Constantine XI died fighting. Mehmed immediately converted Hagia Sophia into a mosque and declared the city the new Ottoman capital.

  6. 6

    Ottoman Istanbul - Capital of an Empire

    1453 - 1923 AD

    For 470 years, Istanbul was capital of the Ottoman Empire at its peak stretching from Morocco to Persia. The city reached its greatest glory under Suleiman the Magnificent (1520-1566). Great architect Sinan built the Suleymaniye Mosque among hundreds of other buildings.

  7. 7

    Modern Istanbul

    1923 - Present

    Republic of Turkey established in 1923; capital moved to Ankara. Istanbul remained Turkey's economic and cultural capital. Population grew from 1 million to 15+ million through mass rural migration. Hagia Sophia became a museum (1934) then reconverted to mosque (2020).

Historical sites

Places where Istanbul's past comes alive.

Byzantine (537 AD)

Hagia Sophia

Where: Sultanahmet

Admission: Free (mosque entry)

Ottoman (1460s-1853)

Topkapi Palace

Where: Sultanahmet

Admission: $15 adults; Harem additional $8

Byzantine (413 AD)

Theodosian Land Walls

Where: Fatih district

Admission: Free

Roman / Byzantine (203 AD)

Hippodrome of Constantinople (Sultanahmet Square)

Where: Sultanahmet

Admission: Free

Byzantine (532 AD)

Basilica Cistern (Yerebatan Sarnici)

Where: Sultanahmet

Admission: $12 adults

Byzantine (4th century AD, mosaics 1316-1321)

Chora Church (Kariye Mosque)

Where: Edirnekapı, Fatih

Admission: Free (mosque); some mosaic sections may have fee

Ottoman (1843-1856)

Dolmabahce Palace

Where: Besiktas

Admission: $18 adults (guided tours only)

Medieval Genoese (1348 AD)

Galata Tower

Where: Karakoy, Beyoglu

Admission: $10 adults