There are different approaches. You can upgrade your walls and most of your weapons gradually. Items are marked with their current and their maximum level. Wooden walls, for example, will eventually become stone walls. The positioning of walls and weapons, however, is crucial as well. It goes without saying that it’s a good idea to optimally protect your king and to refrain from putting your mightiest weapons in the front row.

To rearrange or add to your castle, touch on the "Build" button. Now you can see the number of available and already in-use construction spots. With each level you ascend to, you'll get another spot until the maximum is reached.