Complex sentence: The parish continued to grow and by the 1870s, when it was determined a larger church was needed, the present church (now the Cathedral of the Diocese of Western Massachusetts) was built at a new site on Chestnut Street that was acquired in 1874.
Split into simpler sentences: The parish continued to grow and by the 1870s, when it was determined a larger church was needed. The present church (now the Cathedral of the Diocese of Western Massachusetts) was built at a new site on Chestnut Street that was acquired in 1874.