Heinola is a town and a municipality of 17,953 inhabitants located in the eastern part of the Päijänne Tavastia region, Finland, near the borders of the South Savonia region and the Kymenlaakso region. It is the third largest municipality in the region in terms of population after Lahti and Hollola. The neighbour municipalities of Heinola are Asikkala, Hartola, Iitti, Kouvola, Mäntyharju, Nastola, Pertunmaa and Sysmä.

Iitti is a municipality of Finland. It is located in the province of Southern Finland and is part of the Päijänne Tavastia region. The municipality has a population of 6,444 and covers an area of 687.09 square kilometres (265.29 sq mi) of which 97.27 km2 (37.56 sq mi) is water. The population density is 10.93 inhabitants per square kilometre (28.3/sq mi). Neighbour municipalities are Heinola, Kouvola, Lapinjärvi, Lahti and Orimattila. The municipality is unilingually Finnish.