Lohja has been a focal point for the population and economy of Western Uusimaa since the early 14th century. It was renowned as a trading centre in the Middle Ages. The local inhabitants were among the pioneers of the Finnish mining and construction material industries. By Finnish standards, Lohja has long-established traditions in horticulture and especially in market gardening. These traditions are represented by the symbols of present-day Lohja: limestone and an apple.
Lohja is advantageously located near the Helsinki Metropolitan Area, and it benefits from a good road network. It takes less than an hour to drive from Helsinki to Lohja.
The landscape of Lohja is characterized by manors and gardens. Its area is divided by the Lohja ridge, which forms a watershed for the largest lake system of Southern Finland, Lohjanjärvi. The medieval St. Lawrence church is the architectural highlight of the downtown area, which also includes a heterogeneous mix of buildings mostly dating from the 1960s onwards. The new Lohja Library, opened in 2005, is a distinctly modern building placed in the very centre of the town.
The municipality of Lohjan kunta was consolidated with Lohja in 1997, and the municipality of Sammatti was consolidated with Lohja in 2009. The municipalities of Karjalohja and Nummi-Pusula were consolidated with Lohja in 2013