Complex sentence: Mario (October 18,1810, Cagliari, Sardinia--December 11,1883) was an Italian opera singer, considered to be the most famous tenor of the 19th century.
Split into simpler sentences: Mario (October 18,1810, Cagliari, Sardinia--December 11,1883) was an Italian opera singer. He is considered to have been the most famous tenor of the 19th century.