There are two types of bastions on the fortress wall. The first is an ilchi, a simple, open stonework bastion. The second is a poru, a stonework bastion with a wooden superstructure to offer more cover. Poru literally means “gun tower,” but the guide booklet translates it as “firearms bastion.”
At any rate, this is a close up shot of one of the walls of a poru. The creatures depicted here are doggaebi—mythical creatures similar to ogres but not necessarily evil. The loopholes where the noses would be are for guns.