Numerous watchtowers have also been identified along the Arabian frontier. The Romans reused existing Iron Age and Nabataean structures and built some new ones. They were built on top of hills and ridges where they could be seen from other towers or military posts. One of the best-known examples is Qasr Abu
Rukba. Some speculate that these watchtowers could pass signals by means of smoke during the day and by means of torches at night.
elevation of Qasr Abu Rukba - 87 K]