I built a castle like this for a school project. I had two weeks to build it and make it quite early. The clay I used wouldnt dry so I put it in the oven. I forgot about it and many hours later I remembered, it still appeared to be in good condition so I took it out. When I took it out it fell to pieces and crumbled.
Looks like I had built a castle shortly after cannons were invented. It was the ruins of a destroyed castle!