Complex sentence: By the time of the late Republic expansions and refurbishing of the forums of the city had inspired Pompeii Magnus to create the Theatre of Pompey in 55 BC. The Theatre included a massive forum behind the theatre arcades known as the Poticus Pompius.
Split into simpler sentences: By the time of the late Republic expansions and refurbishing of the forums of the city had inspired Pompeii Magnus to create the Theatre of Pompey in 55BC. The Theater included a massive forum behind the theatre arcades known as the Poticus Pompius.