When designing the tower, I had to make sure it would be big enough to fit the Artillery bases of the Roman bolt throwers on top.
Detail of the gates
I couldn't work out where to put the ladder and so just stuck it to the side of the tower. Later, on futher research, I moved it to underneath the tower and made a hatch for the top.
I added more struts here which gave the tower a more Roman feel and the ladder has been moved.