Complex sentence: The tympanum, or triangular area within the pediment, was often decorated with sculptures and reliefs demonstrating scenes of Greek and Roman mythology or allegorical figures it also consisted of many bright colours suitable to the nature of the building being adorned.
Split into simpler sentences: The tympanum, or triangular area within the pediment, was often decorated with sculptures and reliefs demonstrating scenes of Greek and Roman mythology or allegorical figures. It also consisted of many bright colours suitable to the nature of the building being adorned.