The battlements are on top of the castle, in between the towers. These walkways have raised walls to prevents soldiers from fall off them or being picked off by archers. The walkways have narrow slots carved out at regular intervals for archers to aim through with getting hit themselves. There are also wider slots at longer intervals with cannons stationed at them. Flush against the outside walls are short, long boxes for soldiers to place their extra weapons in when preparing for a seige.
Battlements, Outside Castle
archer
soldier
I'm a soldier. I'm paid to kill. This is a job, nothing more. I'm a mercenary in a lot of ways.
Look here at this map I found. What is the map of? It says there is treasure, marked right here. Hmm it does appear to be close to the battlements... We could sneak off and try to find it. Not like anything is going on anyway, I hate simply standing around. Let us make haste then. Excellent, just lead the way. Alright according to this we need to take the narrow path that diverges from the main path just passed the well. Will it be close to the well then? Just past it.  Let us go before anyone notices. What shall we do with it once we get it?