Several major cities sat on the fertile shores of the Propontis (which is now known as Sea of Marmara): Nicomedia, Chalcedon, Cius and Apamea. Bithynia also contained Nicaea, noted for being the birthplace of the Nicene Creed. It is occupied by mountains and forests, but has valleys and coastal districts of great fertility. The most important mountain range is the (so-called) "Mysian" Olympus (8000 ft., 2500 m), which towers above Bursa and is clearly visible as far away as Istanbul (70 miles, 113 km). Its summits are covered with snow for a great part of the year.