The Downtown Aledo Historic District is a national historic district located in downtown Aledo, Illinois. The district includes 75 contributing buildings and a park. The majority of the buildings are commercial structures, but the district also includes the city's Chicago, Burlington and Quincy Railroad station and both the city's and Mercer County's major government buildings. Development in the district began in the 1850s, and the oldest surviving buildings date from the following decade. The district includes examples of many prominent American architectural styles from the mid-19th century onward; the most prevalent styles are Classical Revival, Romanesque Revival, and Italianate.