In the western reaches of Istanbul's Golden Horn (map) is a district famous in Muslim and Ottoman history, where Ottoman princes would be girt with the Sword of Osman, signifying their ascension as monarch of the Ottoman Empire, the Ottoman equivalent to ascending the throne.
You can go there easily on an inexpensive Istanbul city tour. More...
The mosque of Eyüp is a place of pilgrimage for Muslims, but also for anyone wanting to enjoy a fine view of the city and the Golden Horn from a spot made famous by French naval-officer-and-novelist Pierre Loti.
Here's the story: Ayoub Ansari, standard-bearer of the Prophet Muhammed, is said to have fallen in battle during the attack on the walls of Constantinople by Arab armies in the 700s. He was buried on the shores of the Golden Horn.
In 1453, during Sultan Mehmet II's siege of Constantinople, the grave of the standard-bearer was said to have been miraculously rediscovered, a miracle which inspired the sultan's Ottoman troops to endure the siege and proceed to victory over the Byzantines.
Hence the grave of Ayoub (Eyüp in Turkish) is a sacred site in both religion and Turkish political history, as Eyüp was not only a friend of the Prophet but the key to the greatest Ottoman victory.
Mehmet the Conqueror built a mosque at the site of Eyüp's grave five years after the Conquest, and it became by tradition the place where an Ottoman prince would be girt with the Sword of Osman, signifying his ascension as monarch of the Ottoman Empire.
Because of its sacred and historical importance, many imperial princes and other Ottoman grandees desired to be buried in Eyüp. Soon just about anyone with the money for a gravesite wanted to be buried here, so the Eyüp cemetery extends uphill from the Eyüp Camii (mosque) and tomb almost all the way to the Pierre Loti Café at the top (map).
If you have lots of time in Istanbul, it's fun to visit the mosque and tomb, sense the history, walk or ride the cable car uphill to the Pierre Loti Café to sip a drink while enjoying the panoramic view.
By the way, the great city walls you see extend from Ayvansaray, just east of Eyüp, up and over the hills for 6.5 km (4 miles) to the Fortress of the Seven Towers(Yedikule) and the Sea of Marmara.
City Buses 399 B, C and D, hourly Golden Horn ferries, and taxis take you from Galata Bridge to Eyüp, where there are lots of snack stands and some good restaurants. An easier way is to take a half-day Istanbul city tour that shows you all of the hard-to-reach sights mentioned above. More...