Istanbul City

Istanbul needs 4 days: Hagia Sophia and the Blue Mosque on one, the Grand Bazaar and the Spice Bazaar on another, a Bosphorus boat trip on the third, and the city's Asian side on the fourth. April-May brings mild weather ahead of humid summer heat. It's among Europe's cheapest cities for tourists, with a very favorable exchange rate. It's the only city in the world spanning two continents (Europe and Asia), separated by the Bosphorus strait, and its Hagia Sophia, built as a Byzantine church, converted into an Ottoman mosque and now a mosque again, sums up 1,500 years of religious and political history in a single building.