Hello!
Here is a simple castle made for the challenge. In any case, I didn’t use reference material just yet. But I tried to go over everything. Including deleting doble vertices for the points and towers.
It only consists of 3 objects thanks to the extrusion way of doing things: The entrance is one cube, the walls is another cube but duplicated in edit mode once one wall was finished. And the tower was only one cylinder then duplicated 3 times to make the other towers.
On Edit Mode, its easier to see the lenghts of the block.