The two-chambered room, is situated at the northeastern edge of the castle in a complex section, consisting of the half-moon bastion and a four-sided bastion. It was constructed in 1719-1720, according to the indications of General von Schulenburg.
Actually, it consists of two vaulted longitudinal galleries, with a table-like cross-section, communicating with each other. They run through the thickness of the wall, with a maximum height of 2.48m. The narrow sides facing the outer eastern perimeter of the wall bear embrasures for cannons.
The term “casamatta” (casemate) refers to the low enclosed gun emplacement within the thickness of the wall, covered entirely by vaults supporting the upper platform.