1 Kings 9:15
And this is the reason of the levy which king Solomon raised; for to build the house of the LORD, and his own house, and Millo, and the wall of Jerusalem, and Hazor, and Megiddo, and Gezer. And this is the reason of the levy which king Solomon raised; for to build the house of the LORD, and his own house, and Millo, and the wall of Jerusalem, and Hazor, and Megiddo, and Gezer.
The levy was raised to pay for the house of the Lord and the king's own house, and for Millo and the wall of Jerusalem, together with Hazor, Megiddo, Gezer and other cities. The cities named, above all Gezer and Megiddo, lay upon important thoroughfares of travel and at gateways of the nations, and they were rebuilt and fortified as strong centers. This vast program of building came from ambition to outdo all other nations in outward grandeur.
Its extravagance laid heavy taxation upon the poor, showing what it costs when outward display and worldly power are sought at the sacrifice of right principles. Placed as they were, these fortified cities could have made Israel known to travelers from many lands and spread the knowledge of the true God. Instead they were used to build up Solomon's own strength and security, so the opportunity to enlighten the nations was lost and multitudes remained in ignorance of God.