Yes, you can leave Istanbul Airport (IST) during an international layover, provided you meet the entry requirements for Turkey. For most travelers in 2026, this requires obtaining a Turkish e-Visa in advance or being from a visa-exempt country. If your layover is at least 6 to 10 hours, you can clear immigration and take a taxi or the M11 metro line to the city center, which takes about 45 to 60 minutes. Turkish Airlines even offers a free tour service called Touristanbul for passengers with layovers between 6 and 24 hours, which handles the logistics of seeing major sites like the Hagia Sophia and Blue Mosque. However, you must ensure you have enough time to clear security and passport control upon your return, which can be busy. As of 2024, travelers from certain countries (including India and Afghanistan) connecting to specific North/South American destinations now need an "Airport Transit Visa" even if they don't leave the transit area, so always check the latest rules for your specific nationality. If you only intend to stay in the terminal's international zone, no visa is required, but a quick trip into Istanbul is a highly recommended way to break up a long journey.