Complex sentence: However, it also includes a rectory and a villa (counted in the overall area), which are not strictly part of the church, and it can accommodate 18,000 worshippers, compared to 60,000 for St. Peter's.
Split into simpler sentences: However, it also includes a rectory and a villa (counted in the overall area), which are not strictly part of the church. It can accommodate 18,000 worshippers, compared to 60,000 for St. Peter's.