Marengo is a town in Liberty Township, Crawford County, Indiana, United States. The population was 828 at the 2010 census. One of the tourist attractions and sources of revenue for the town is Marengo Cave, a U.S. National Landmark. Originally discovered in 1883 by two school children, it today offers guided tours.
Marengo was devastated by an F3 tornado in 2004, resulting in damage to nearly 75 percent of the town and the death of one resident. According to the 2010 census, the town has a total area of 0.77 square miles (2.0 km2), all land.