Assertion: fortress's tower | /r/AtLocation | wall
Facets:
value: to improve defence
type: PURPOSE
value: as with roman and earlier architecture
type: OTHER
value: usually
type: TEMPORAL
Source sentences:
text: Towers were added to walls so that the defenders could fire down onto the enemy from multiple angles.
text: As with Roman and earlier architecture, projecting flanking towers were usually added to the wall to improve defence.