'Tower' in the Bible

"Hear another parable. There was a man who was a master of a household, who planted a vineyard, set a hedge about it, dug a winepress in it, built a tower, leased it out to farmers, and went into another country.

He began to speak to them in parables. "A man planted a vineyard, put a hedge around it, dug a pit for the winepress, built a tower, rented it out to a farmer, and went into another country.

Or those eighteen, on whom the tower in Siloam fell, and killed them; do you think that they were worse offenders than all the men who dwell in Jerusalem?

For which of you, desiring to build a tower, doesn't first sit down and count the cost, to see if he has enough to complete it?