When I visited St. Michael's Mount the tide was out but imagine it surrounded by the sea - the perfect stronghold, protected from attack on all sides.
In The Lord of the Rings by J.R.R.Tolkien, Aragorn and the people of Rohan run to take refuge in the stronghold, Helm's Deep. It is a place of safety as it is protected on three sides by a mountain. They know of no better hiding place.
The Lord is good, a stronghold in the day of trouble; he knows those who take refuge in him. Nahum 1:7
The Lord has become my stronghold, and my God, the rock of my refuge. Psalm 94:22
In these days of trouble we need to run to our God.
The Lord is the stronghold of my life; of whom shall I be afraid? Psalm 27:1
As well as Helm's Deep, there is the stronghold of Isengard ruled by the evil Saruman. His stronghold needs destroying, not running to!
The enemy also has strongholds in our lives - things like fear and worry. Our God gives us the strength and ability to fight these other strongholds and destroy them.
The weapons of our warfare are not of the flesh but have divine power to destroy strongholds...and take every thought captive to obey Christ. 2 Corinthians 10:4