Complex sentence: During the fire many art masterpeices were destroyed, probably including Michelangelo's "Cupid", a famous sculpture bought as part of the Gonzaga collections in the XVII century.
Split into simpler sentences: During the fire many art masterpeices were destroyed. Probably it was lost in that occasion the Michelangelo's "Cupid", a famous sculpture bought as part of the Gonzaga collections in the XVII century.