The Old City also known as Stamboul or Eski Istanbul, spreads acroseseven hills and is home to the city's richest historic treasures Haghia Sophia, the Covered Bazaar, the Blue Mosque, Topkape Palace, the Seleymaniye Mosque, and the Church of St. Saviour in Chora.
Stamboul has no hills and is not near the Haghia Sophia.  