Originally a one-storey building, erected by Bernardo Morando in the 1580s, then rebuilt ca. 1630 - it was one of the first public buildings in the city of Zamosc.
External stairway placed over the portal leads to a low ground floor of this 63-meter long building.
At present it houses a military museum (the Arsenal Museum) that displays a modest collection of 17th c. cannons, swords, muskets, cold steel, firearms and and an exhibition presenting the history of Zamość fortress including a model of the town.