Sponsored Topics. Arenzville is a village in Cass County, Illinois, United States. The population was 409 at the 2010 census. Arenzville is located at 39°52′39″N 90°22′15″W / 39.8775°N 90.37083°W / 39.8775; -90.37083 (39.877519, -90.370955). According to the United States Census Bureau, the village has a total area of 0.8 square miles (2.0 km²), all of it land.