Vienna is a city in Johnson County, Illinois, United States. The population was 1,434 at the 2010 census. It is the county seat of Johnson County, and the site of two well-known state penitentiaries. Heron Pond - Little Black Slough Nature Preserve, a National Natural Landmark, is nearby. The Tunnel Hill State Trail trail-head and headquarters is located in Vienna. The Trail of Tears halfway point commemorative totem and flags are located in the adjacent city park. The town's name is pronounced differently from the English name for the Austrian capital of the same name.
Vienna is located at 37°24?58?N 88°53?39?W / 37.41611°N 88.89417°W / 37.41611; -88.89417 (37.416103, -88.894268).
According to the United States Census Bureau, the city has a total area of 2.2 square miles (5.8 km²), of which, 2.2 square miles (5.8 km²) of it is land and 0.44% is water.