Rostov (Great) was founded in 862 and was the trade and economic center of the Yaroslavl province. Rostov is located on the western shore of Lake Nero, which is about half a million years old, one of the few lakes in Central Russia dating back to the pre-glacial period.
Nero is the largest lake in the Yaroslavl region, while its average depth is only 1.5 - 2 meters, the greatest depth is 4 meters, the reason for this is sediments at the bottom of sapropel (centuries-old bottom sediments).
Nero is gradually becoming swampy, this is a natural aging process that will last for many years, human activity has significantly accelerated the aging of the lake, the long-standing and strong plowing of the Rostov basin, massive deforestation, and in more recent times, industrial and domestic wastewater. The life cycle of the ancient lake is ending, but despite this, Nero will continue to exist in a different form.