The Green Tomb at Bursa, built by Sultan Mehmet I (the 5th Sultan) in 1421, close to the Green Mosque. Bursa is the fourth largest city in Turkey and the first Ottoman Capital. Bursa contains the Mausoleum of Osman 'Bey' ('Sultan'/'Chieftain') (1258 - 1356), founder of the Ottoman Empire as well as two world famous Sufi Saints. Historically also known Prussa and later Brussa or Brousse. On the northwestern slopes of Mount Uludag in the south of the Marmara region. Known as Yesil Bursa (Green Bursa), because of many parks and gardens as well as vast forests. The area is rich in archaeology.