Finnish regional road 120 (Vihdintie) between Helsinki and Vihti, one of the most important road connections from Lahnus to the capital, passes through the district.[3] Along the road, at the intersection near the Shellfilling station, the north branch road to Klaukkala is Lahnuksentie (Mt 1324).[4] There are also several nature reserves in Lahnus: Tremanskärr Nature Reserve and Luukki Nature Reserve, as well as part of Nuuksio National Park.
Lahnus is an old village name and has been spelled, among others: Lanoxby (1540), Lanos (1541), Lanas (1547), Lora (1558), Loureby (1559), Lahcnus (1563) and Lahnås (1594).[5] The name is probably of Finnish origin, but the meaning is unclear.[6] The highest daily rainfall in Finland was measured in Lahnus: on July 21, 1944, it was 198 millimeters.[7]