The mysterious Sabailovsky Castle, shrouded in legends and legends, is of particular interest, because it is located right under the water, 350 m from the shore and is often called an underwater city for this reason. It was erected on a rocky island in Baylovskaya Bay by Shirvanshah Fariburz III, in 1235. Presumably, the castle was built for defensive purposes, as a defensive sea fortress, which at the same time served as the residence of the Shirvanshahs. Its necessity was explained by the potential danger of an enemy attack from the sea.
In this regard, the Shirvanshahs formed a navy at the end of the XII century, which surrounded the fortress. This is confirmed by stones with a hole for tethering vessels, which are visible from the outside around the wall. In the XIII century, the Mongols, who did not have a navy, tried for a long time to conquer the fortress. But, despite the fact that they destroyed its upper part with siege weapons, they never managed to conquer the Sabailovsky castle. In 1306, due to the strongest earthquake that occurred in the south of the Caspian Sea, and sea level rise, the fortress sank into the water. From the beginning of the XIV century to the beginning of the XVIII century, the structure was flooded by the waters of the Caspian Sea. In 1723, due to the lowering of the Caspian Sea level, the top of the tower appeared out of the water. The top of the structure is completely destroyed, only the lower part of the walls and towers has been preserved, reaching about 1.5-2 m in height in places.
Archaeological studies of the fortress have shown that the foundations of 9 residential premises have been preserved, 2 of which had hearths. About 700 stones with inscriptions, fragments of black and red fired pottery, whole vessels, copper coins of Shirvanshah Kershasba (1203/4-24), etc. were collected from the bottom of the sea. And today, some of the stones raised from the bottom of the sea are in the museum of the Shirvanshahs' Palace.