Complex sentence: It was also known as "Mercado" (or "Plaza") "11 de septiembre" (11th of September Market or plaza); the name "Plaza Miserere" dates from 1947.
Split into simpler sentences: It was also known as "Mercado" (or "Plaza") "11 de septiembre" (Market or plaza 11th of September). The name "Plaza Miserere" dates from 1947.