The wall walk is only partly solid; arches stabilize the inner side. Some of the arches are punctuated with arrow slits.
These arrow slits are inside niches, in German they are called Schartennischen, to allow the defenders to aim and point their weapons properly. Actually, arrow slits are less frequent as one may think. Many of them are some sort of window or they are an element of psychological warfare. Iíve visited many castles, where possible arrow slits turned out to be simple windows. It is very easy to determine whether the slits could have been use for warfare or not. Just look, if there is a niche or not. Without niche, the slit is unusable.
I have just visited Linn castle again and taken some photos.
The first picture shows a typical arrow-slit through a wall (outer ward). The second picture is a "cut through arrow-slit" of the outer ward. The third picture finally shows a mock arrow-slit of the oldest tower. This tower dates back to the late 12th century and as you can clearly see, it is not really functional, as the wall is 1.5 metres thick and you can only see a tiny part of the surrounding landscape. You cannot aim with a crossbow or bow properly.
Wehrgang der Vorburg The wall walk of the bailey
The length of an arrow slit may be a hint for its age. Long slits (2 metres) date back to the 13th century. Throughout the decades of the 14th century, the slits became shorter. In the middle of the 15th century they were adjusted to new firearms and were shaped like reversed keyholes. In German they are called Schluessellochscharte.
Letís turn to the merlons.
Merlons were meant to protect the defenders. The current use of many Legoģ castles is simply senseless, as they are far too low. A proper merlon is taller than a man, usually up to 2 metres. They may also carry arrow slits. As a demonstration i have added three pictures from Linn castle.
Below is a list of links of castles, which have influenced the wall walk of the bailey of Drachenfels castle. They are all in German. Unless you speak German, you have to focus on the pictures.