The watchtower was sometimes used as a lookout for the enemy (2 Chronicles 20:24; Isaiah 21:8; 32:14).
Watchtowers, or just towers, were also built in the fields. They might provide a place for a watchman to keep watch over the field (Isaiah 5:2; Matthew 21:33). Stones were picked up out of the fields to make the tower which also served as a place for workmen to go for shade in the heat of the day.
The only place we see watchtowers today is in the West Bank, and these are usually off the main roads. During the past few years I have photographed several of these old watchtowers. So far as I know they are no longer in use. I am sure that I have shown some watchtowers before, but I thought you might enjoy some of these new photos.