Complex sentence: In the 1940s Sisterna arrived in Mar del Plata, the most important coastal city of Argentina, where he soon formed a team with Demetrio Elíades, the owner of the Confitería Havanna situated in downtown Mar del Plata.
Split into simpler sentences: In the 1940s arrived in Mar del Plata, the most important coastal city of Argentina, where he soon formed a team. The owner of the Confitería Havanna situated in downtown Mar del Plata.