The Great Armoury was built in 1600-09 on the medieval line of the city walls. A working arsenal until the 1800's, the armoury remains the finest example of Renaissance architecture in the city. It was designed by Opberghen and is the most impressive of his works in Gdańsk. The well-like structure in front was used as an elevator to transport gunpowder and cannon balls from their storage place in the basement. The armoury was badly damaged in WWII and had to be completely rebuilt and its only in recent years that it has regained its former glory following a spell during which it even placed host to a supermarket. It's now open occasionally as an art gallery. There is a smart little cafe on the ground floor which gives you a chance to take a look inside when there's no exhibitions taking place.