Complex sentence: As a young man, he accepted employment with an Irish architect in Washington D.C., but returned to New York to join the firm of architect Peter B. Wight, the beginning of a life-long friendship between the two.
Split into simpler sentences: As a young man, he accepted employment with an Irish architect in Washington D.C., but returned to New York to join the firm of architect Peter B. Wight. This was the beginning of a life-long friendship between the two.