Megiddo was a royal city built by Solomon, as evidenced by the style of the capitals (shown in the picture) at the top of the columns.
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.
Often we think of Israel as just Jerusalem and Bethlehem, but it was a nation of many fortified cites. Megiddo goes back to the time of Joshua
Joshua 12:21 The king of Taanach, one; the king of Megiddo, one;
Megiddo was where good King Josiah was killed by Pharaoh Necho:
2 Kings 23:29 In his days Pharaohnechoh king of Egypt went up against the king of Assyria to the river Euphrates: and king Josiah went against him; and he slew him at Megiddo, when he had seen him.
And is where the battle of Armageddon (mound of Megiddo) will be:
Revelation 16:16 And he gathered them together into a place called in the Hebrew tongue Armageddon.