Complex sentence: Diodorus Siculus added that Actis, one of the sons of Helios and Rhode travelled to Egypt where he built the city of Heliopolis and he taught the Egyptians the science of astrology.
Split into simpler sentences: Diodorus Siculus added that Actis, one of the sons of Helios and Rhode, travelled to Egypt. He built the city of Heliopolis and taught the Egyptians the science of astrology.