Lohja is a town in Finland, located in the southern interior of the country. Lohja is situated in the western part of the Uusimaa region. The population of Lohja is approximately 46,000. It is the 25th most populous municipality in Finland. Lohja is part of the Helsinki sub-region, but not directly part of the Helsinki metropolitan area.

Uusimaa is a region of Finland. It borders the regions of Southwest Finland, Tavastia Proper (Kanta-Häme), Päijänne Tavastia (Päijät-Häme), and Kymenlaakso. Finland's capital and largest city, Helsinki, along with the surrounding metropolitan area, are both contained in the region, and Uusimaa is Finland's most populous region. The population of Uusimaa is 1,734,000.