Complex sentence: At this point--twenty years old and approaching graduation--an opportunity was presented to him, that would be his life's journey, and it would begin with a required sojourn in Florence, Dante's home.
Split into simpler sentences: At this point--twenty years old and approaching graduation--the opportunity of a lifetime was presented to him. It would be his life's journey and it would all begin with a required sojourn in Florence, Dante's home.