The 7-storey Grand Mill in Gdansk was built in the mid-16th century on a channel of the Radunia River, and served as a granary and a bakehouse as well as a corn mill. Its stones were powered by 18 overshot 5 m diameter waterwheels. It operated until 1945 and was reconstructed after war damage in the 1960s. All the machinery was removed, but it remains a conserved historic monument. After several years of use as a shopping centre and renewed restoration now it houses an amber museum. In the 15th century it was the largest building in Europe concerned with manufacturing.