Greensburg is a city in Decatur County, Indiana, United States. The population was counted at 11,492 at the 2010 census. The city is the county seat of Decatur County.
According to the United States Census Bureau, the city has a total area of 4.8 square miles (12.5 km²). 4.8 square miles (12.4 km²) of it is land, and 0.04 square miles (0.1 km²) of it (0.83%) is water.
The Decatur County Courthouse in Greensburg, Indiana, is known for a tree which grows from the top of the Courthouse Tower, giving Greensburg its nickname of the "Tree City.”