Complex sentence: The building's crossing received a tiled hipped roof and an oculus, which lit the interior of the church, and was added above the renovated dome, which had a frescoed ceiling decorated with bronze designs as opposed to the gold leaf present before the earthquake.
Split into simpler sentences: The building's crossing received a tiled hipped roof and an oculus, which lit the interior of the church, and was added above the renovated dome. The new dome had a frescoed ceiling decorated with bronze designs as opposed to the gold leaf present before the earthquake.