Complex sentence: Over the course of time, the fortification systems were improved: the outer walls of the defenses were faced with stone blocks, the moat was broadened and forward defences were added in front of the rampart.
Split into simpler sentences: Over the course of time, the fortification systems were improved. The outer walls of the defenses were faced with stone blocks, the moat was broadened and forward defences were added in front of the rampart.