The port city of
Surabaya is built along the river. The old Surabaya harbour, built centuries ago, is located near the
river mouth. At one point in time, this was an entry port to the
Kingdom of Majapahit, and it is also here that the founder of the Majapahit empire (
Raden Wijaya) fought off a
Mongol invasion in 1293. During the times of the
Dutch East Indies, this river was heavily utilized as a goods transport route. Large trade ships unload commodity goods at the
Strait of Madura, where smaller ships take over and distribute the trade goods inland. The
Kali Mas harbour was built to facilitate such trade. The areas along Kali Mas were split into two, which are called
Westerkade Kalimas (west of Kali Mas) dan
Oosterkade Kalimas (east of Kali Mas), and in the local dialect are known as
Kulon Kali and
Wetan Kali respectively. The areas east of the river were developed for trade and commercial activities. These include Kembang Jepun, Cantikan, Kapasan. The west side includes Gresik Road, Kalisosok, and the area around west Tanjung Perak. With the development of land-based transport river transport along the Kali Mas has largely been diminished. Due to its long history serving as a major transport route, many historical buildings can be found along the river bank. These include the Kali Mas harbour, old settlements and trading houses along the river banks, as well as the residence of the governor. There is also a collection of old bridges, including the famous historical landmark
Jembatan Merah (
Roode Brug), as well as a
drawbridge (which is no longer operating). ==Current use==