Osman Gazi, the founder of the Ottoman Empire, lived between the years (1258 and 1324 AD), and was buried in the mausoleum that was erected in the chapel of the Byzantine monastery. At the hands of Sultan Abdülaziz, it remained faithful to its ancient structure, which is a wooden coffin inlaid with mother-of-pearl in the center of the tomb surrounded by a balustrade decorated with mother-of-pearl, and embroidered with silver on velvet, which shows the dates of Osman Ghazi’s personality, his birth, year of rule and death.