Right across from the cistern is the greatest single building in a city full of wonders, the Hagia Sophia or Aya Sofya (£8.70, closed Mondays). It was a church, then a mosque and is now a museum.
The four courtyards and plethora of buildings and pavilions that make up the Topkapı Palace complex (topkapisarayi.gov.tr ; £8.70, closed Tuesdays in winter) are a whole afternoon’s entertainment.
