Muslim pilgrims from all over the world make their way to the brightly colored, tile-covered tomb of Eyüp Ensari (Ayyub al-Ansari)—a companion of the Prophet Muhammad who served as his standard-bearer—at this mosque complex on the Golden Horn. Ensari was killed during the first Arab siege of Constantinople (AD 674–78), and the eternal presence of a man so close to Muhammad makes this the holiest Islamic shrine in Turkey. His gravesite was visited by Muslim pilgrims in Byzantine times and "rediscovered" during Mehmet the Conqueror's siege of Constantinople. After the conquest, Mehmet monumentalized the tomb and built a mosque, where investiture ceremonies were held for successive sultans; the mosque currently on the site was built after the original edifice was ruined in the earthquake of 1766. The plane-tree-shaded courtyards and large numbers of visitors—particularly at midday Friday prayers—imbue Eyüp Sultan Camii with a sense of peace and religious devotion not found in many other parts of this often frenetic city. A vast cemetery has grown up around the mosque, including the grand tombs of many other distinguished departed. It's best to avoid visiting at prayer times.