Some ramparts and walls still survive on the steep cliff, the site of Bursa's citadel and oldest neighbourhood, Tophane. From Ulu Camii, walk west and up Orhan Gazi (Yiğitler) Caddesi, to reach the Hisar (Fortress). On the summit, a park contains the Tombs of Sultans Osman and Orhan , the Ottoman Empire's founders.
Although ruined in the 1855 earthquake, Sultan Abdülaziz rebuilt the mausoleum in baroque style in 1863. Osman Gazi's tomb is the more richly decorated.
The six-storey clock tower , the last of four that also served as fire alarms, stands in a square with a cafe where families and couples gaze out over the valley and snap photos.
