Complex sentence: The three towers were tapered at the base, and the curved asymmetric legs of the towers created a significant technical challenge, and substantial temporary structures were necessary to support the legs of the tower while they were under construction.
Split into simpler sentences: The three towers were tapered at the base, and the curved asymmetric legs of the towers created a significant technical challenge. Substantial temporary structures were necessary to support the legs of the tower while they were under construction.