'Stronghold' in the Bible

When [the] Philistines heard that they had anointed David as king over Israel, all [the] Philistines went up to seek David, but David heard and went down to the stronghold.

I take refuge in God, my rock, my shield, and the {strength} of my salvation. My stronghold and my refuge, O my savior, you will save me from violence!

Now at that time, David [was] in the stronghold, and a garrison of [the] Philistines [was] in Bethlehem at that [same] time