Note: This is a guest post since presently I am busy today teaching class online for seminary students overseas. This is by Cowboy Bob. His blog be found here and he runs The Question Evolution Project on Facebook here.
Throughout much of history, people have used watchtowers for various purposes. East Berlin had several (with one remaining) to alert guards of people trying to escape their socialist paradise. Towers were set up to watch for fires. See a movie about the cavalry in a Western movie and notice the towers to watch for attackers.
It was very common for cities and castles to have walls built to keep out marauders, and of course, those had towers as well. However, towers were not the only place for sentries and lookouts; they also walked on those thick walls.
The Domain for Truth 