: Early medieval strongholds featured earthworks and timber-frame "box" ramparts filled with earth, as seen in the Lusatian culture at Biskupin, Poland .
In religious literature, "stronghold" takes on a dual meaning as both a place of divine safety and a spiritual prison.
: The invention of gunpowder and cannons in the 15th century made vertical stone walls obsolete, as they could not deflect the momentum of modern projectiles. This led to a reconfiguration of urban settlements, separating administrative strongholds from mercantile cities. Theological and Spiritual Context