Come to Bursa, due south of Istanbul across the Sea of Marmara (map), for its beautiful mosques and other early Ottoman architecture, for its silk-filled bazaars, its thermal spa baths and hotels. You can visit Bursa to see the top sights on a day-trip excursion from Istanbul, although an overnight in Bursa is more comfortable and rewarding. Bursa was the first capital (late 1200s-early 1300s) of the Ottoman Empire. The two founding sultans, Orhan and Osman, are buried here, and this is where the empire's great architectural style was first developed. On Bursa's western outskirts is Çekirge, a thermal spa resort since Roman times, with many spa hotels and bathing establishments. Some people come for İskender kebap, slices of grilled lamb dressed with savory tomato sauce and browned butter. (On that subject, here's a funny sign.) From Güzelyalı or Mudanya you can get to Bursa by bus and Bursaray (Metro). From Yalova, take a bus to Bursa, or a minibus to İznik. After touring İznik, you can catch a minibus onward to Bursa.