'Strongholds' in the Bible

He has stretched out His hand over the sea,He has shaken the kingdoms;The Lord has given a command concerning Canaan to destroy her strongholds and her fortresses [like Tyre and Sidon].

Thorns will come up in its fortified palaces,Nettles and brambles in its fortified cities;It will be a haunt for jackals,An abode for ostriches.