'Tower' in the Bible

“Listen to another parable. There was a landowner who planted a vineyard and put a wall around it and dug a wine press in it, and built a tower, and rented it out to vine-growers and went on a journey.

And He began to speak to them in parables: “A man planted a vineyard and put a wall around it, and dug a vat under the wine press and built a tower, and rented it out to vine-growers and went on a journey.

Or do you suppose that those eighteen on whom the tower in Siloam fell and killed them were worse culprits than all the men who live in Jerusalem?

For which one of you, when he wants to build a tower, does not first sit down and calculate the cost to see if he has enough to complete it?