Complex sentence: Construction started in 1764 and the new larger structure with one nave and a vaulted ceiling was completed in 1767 but the ceiling collapsed killing 90 people due to the lack of supporting pillars.
Split into simpler sentences: Construction started in 1764 and the new, larger structure, with one nave and a vaulted ceiling, was completed in 1767. However, the ceiling collapsed killing 90 people, due to the lack of supporting pillars.