Address: Helsingintie 223 Orimattila
The Tönnö museum bridge, the only site of the Finnish Road Museum in the Päijät-Häme region. The arched bridge is 37 metres long and 6.5 metres wide and was designed by Jalmar Castrén in 1911 and it is Finland's oldest reinforced-concrete road bridge.
The surroundings of the Tönnö museum bridge, The Tönnönkoski rapids, are listed as nationally important cultural landscape. The long history of settlement in the Porvoonjoki River valley is evident here. Archaeological surveys have revealed numerous Stone Age dwelling sites in the vicinity of the rapids.
The earliest information on a mill built in the rapids is from 1586. As many a four mills have operated at the same time in the rapids. At present, there are two flour mills and the remains of a sawmill. The older mill (Niemen mylly) is from the 19th century. It went out of use in 1967. The later mill, known as Tönnön mylly, dates from the early 1900s and is still in use.
Next to the bridge is an information sign on the history of the region.