The well is placed in the Arsenal building and it represents a masterpiece of architecture and construction.

It is an integral part of unique water supply system of the Fortress. As a component of the Underground military galleries, in a case of great siege, it was able to supply the entire Fortress with drinking water.

It was built during the second decade of 18th century, located in the eastern part of the Upper Fortress, abaft the courtine which connects bastions of St. Innocent and St. Joseph.