This is a secret tunnel with a length of almost 100 metres and width of about 2, constructed in the wall of the Bastion when the fortress was rebuilt from wood and earth into stone. For defence purposes it was never used, and in the end served as a storage room. Restoration of the gallery and Casemates was a gift from the Kingdom of the Netherlands for the 300th birthday of St. Petersburg. Since then it has been open to visitors of the fortress. It is dark and cool inside, and in the dungeon, a roomy hall host exhibitions, theatre performances, conferences, and seminars.