Complex sentence: The foundation of the building is comprised of vaults resting on Romanesque and Byzantine capitals which, along with the fact that there are no Gothic or Muslim architectural features, suggest that the original building predates the Crusader period.
Split into simpler sentences: The foundation of the building is comprised of vaults resting on Romanesque and Byzantine capitals. Along with the fact that there are no Gothic or Muslim architectural features, this suggests that the original building predates the Crusader period.