The banks of the river are dotted with historical and cultural sites, including the medieval monasteries of Murom, the mosques and minarets of Kasimov, the fortified kremlins of Kolomna and Serpukhov, the memorial houses of Vasily Polenov and Sergey Yesenin, the excavated ruins of Old Ryazan and the Oka Shukhov Tower.

Oka River, river in western Russia. It is the largest right-bank tributary of the Volga. Rising in the Central Russian Upland, it flows 932 miles (1,500 km), first north in a rather narrow, winding valley to Kaluga, then sharply eastward across a broad lowland to join the Volga at Nizhny Novgorod.

The Oka river is one of two major tributaries of the Volga, and its basin borders on that of the Dnipro, which is why Kievan Slavs – led by their Viking princes – used it as the main route for colonising the lands that form the historic core of what we now know as Russia.

It originates in the Oka Lake, Oka Plateau, Sayan Mountains at the western end of Buryatia. It flows roughly northwestwards with the Bolshoy Sayan to the southwest. After it bends northeastwards the river flows between the Kropotkin Range and the Belskye Goltsy (Бельские Гольцы).