Complex sentence: The damage done to the citadel during the siege, primarily on its eastside, was repaired, the mosque was reconstructed and enlarged, the towers were repaired and the tiles of the Blue Dome, which had been destroyed, were replaced by lead plates.
Split into simpler sentences: The damage done to the citadel during the siege, primarily on its east side, was repaired. The mosque was reconstructed and enlarged, the towers were repaired, and the tiles of the Blue Dome, which had been destroyed, were replaced by lead plates.