Complex sentence: Noted abolitionist Dr. Samuel Osgood was the pastor of the congregation from 1809 to 1854, during which time the present building was visited by notable figures such as Daniel Webster and John Brown, who resided in Springfield for some time.
Split into simpler sentences: Noted abolitionist Dr. Samuel Osgood was the pastor of the congregation from 1809 to 1854. It was during this time that the present building was visited by notable figures such as Daniel Webster and John Brown, who resided in Springfield for some time.