Topkapi Palace was the official and primary residence in the city of the Ottoman Sultans for 400 years of their 624-year reign,from 1465 to 1856.Topkapi Palace is the most popular attraction in the city, so you should put it on top of your list and get here early, before 9:00 a.m., to beat the crowds and long lines. The palace originally had 5,000 residents, functioning as an opulent, self-contained city divided in various sections that cover a total area of 700,000 square yards, all surrounded by 3 miles of walls. Four large courtyards with impressive column arcades enclose beautiful gardens you are welcome to stroll through, amid lush landscaping, ponds and fountains. It was home to the royal Sultan and the empire's center of government for four hundred years; it also housed the judiciary, Harem and the Palace School. Because there are so many interesting things to see, a visit will take at least three hours for the complete visit.