Troy is a city in Pike County, Alabama, United States. The city is the county seat of Pike County. It was formally incorporated on February 4, 1843.As of the 2010 census, the population was 18,033. The 2015 estimated population was 18,696. The City of Troy is considered one of the fastest growing cities in Alabama. Troy is a college town and is home to Troy University, the third-largest university in total enrollment in the state of Alabama.