Matthew Poole and continuators on Judges 9:46

46 ¶ And when all the men of the tower of Shechem heard that, they entred into an hold of the house of the god of Berith .

A strong place belonging to the City of Shechem, and made for its defence or security, but without the City. It is thought, this was that Millo which was confederate with Shechem in their design against Abimelech, v. 6. which also Iotham Cursed with Shechem, v. 20. and that Curse is noted to have its Effect, v. 57. And this place may be called the Tower of Shechem; either because those who possessed and defended it, were sent from Shechem: Or, because it was built and kept for the safe-guard of Shechem.

Or, Baal-berith, v. 4. Hither they fled out of the Town belonging to it, fearing the same event with Shechem; and here they thought to be secure; partly by the strength of the place, as the Temples of Idols were oft-times built in the highest and strongest Places, as the Capitol at Rome, and the Temple at Ierusalem; and such this place seems to have been, because they laid their Treasure here, v. 4. Partly by the Religion of it, thinking that either their god would Protect them there, or that Abimelech would spare them there, if not out of piety to that god, yet out of thankfulness for the benefit which he received thence, v. 4.