'Tower' in the Bible

Hear another parable: There was a man that was a householder, who planted a vineyard, and set a hedge about it, and digged a winepress in it, and built a tower, and let it out to husbandmen, and went into another country.

And he began to speak unto them in parables. A man planted a vineyard, and set a hedge about it, and digged a pit for the winepress, and built a tower, and let it out to husbandmen, and went into another country.

Or those eighteen, upon whom the tower in Siloam fell, and killed them, think ye that they were offenders above all the men that dwell in Jerusalem?

For which of you, desiring to build a tower, doth not first sit down and count the cost, whether he have wherewith to complete it?