Jeremiah 52:4

And it came to pass in the ninth year of his reign, in the tenth month, in the tenth day of the month, that Nebuchadnezzar, king of Babylon, came, he and all his army, against Jerusalem and pitched against it, establishing the camp of the besieging army, and built forts against it round about, very likely towers of wood used for purposes of observation and as foundations for casting missiles into the city.