Complex sentence: It is best known for being one of the first casinos of Chile; one operated in the building between 1917 and 1931, after which all casinos except the newly opened Casino de Viña del Mar were declared illegal.
Split into simpler sentences: It is best known for being one of the first casinos of Chile; one operated in the building between 1917 and 1931. After 1931 all casinos, except the newly opened Casino de Viña del Mar, were declared illegal.