Things to Do in Istanbul: Hagia Sophia, the Blue Mosque & the Bosphorus

What to see in Istanbul — top sights

• Hagia Sophia — built as a cathedral in 537, later an imperial mosque, then a museum, and a mosque again since 2020. Its dome was the largest in the world for close to a thousand years.
• The Blue Mosque (Sultan Ahmed Mosque) — the early-17th-century imperial mosque facing Hagia Sophia, named in English for the Iznik tiles lining its interior.
• Topkapı Palace — the Ottoman sultans' principal residence for roughly four centuries, overlooking the point where the Bosphorus meets the Golden Horn.
• The Grand Bazaar — one of the largest and oldest covered markets in the world, with thousands of shops across a roofed street grid.
• The Basilica Cistern — the vast columned Byzantine water cistern beneath Sultanahmet, including the two re-used Medusa head bases.
• The Bosphorus — the strait itself is the sight: public ferries cross between the European and Asian shores and are the cheapest way to see the city from the water.

Why visit Istanbul

Few cities let you walk between a sixth-century cathedral, an Ottoman palace and a covered market of thousands of shops inside an afternoon, then cross to another continent by public ferry for the price of a bus ticket. Istanbul is the rare destination where the headline sights are genuinely concentrated rather than scattered.

FAQ

How many days do you need in Istanbul?

Three to four nights covers the historic peninsula — Hagia Sophia, the Blue Mosque, Topkapı and the bazaars — with time for a Bosphorus ferry and a day on the Asian side. Two nights is enough only for Sultanahmet itself.

Is Istanbul in Europe or Asia?

Both. The Bosphorus strait runs through the city, putting the historic centre on the European side and districts such as Kadıköy and Üsküdar on the Asian side. Public ferries cross between them throughout the day.

Can you visit Hagia Sophia and the Blue Mosque?

Both are working mosques and open to visitors outside prayer times. Dress modestly, remove shoes before entering the prayer hall, and expect access to be restricted during the five daily prayers and Friday midday prayers.