The stone-age dwelling-place in the Ristola district of Lahti is among the oldest known habitations in Finland. The first mention of Lahti in the records is in 1445. At that time, the village called Lahti was part of the Hollola parish. In the 1870s, Lahti was a typical local main-street village beside the highway from Hämeenlinna to Vyborg. When the Riihimäki-St. Petersburg railway was opened to traffic in 1870, followed by the Vääksy canal the next year, life in the village became busier.
Lahti was officially recognized as a market town in 1878 and received its town charter in 1905. Thanks to its good traffic connections, industries grew up in Lahti, including metal, glass, joinery and textiles. The development of the city can be divided into several quite clear periods. The uniform wooden construction of the market-town period was followed by the Jugend city centre of the early 1900s. The most important building of this era is the Town Hall (1912), designed by Eliel Saarinen. Also dating from this time are the Hennala Garrison area and the Anttilanmäki district with its wooden houses; both these areas are of national importance.
The 1930s constituted a period of vigorous construction activity, giving birth to buildings that dominate the city landscape and are also architecturally significant. The building boom culminating in the early 1970s produced an ever-increasing shift in habitation away from the city centre to new suburbs, but also a further building up of the city centre as business life developed. In the new millennium, a former industrial area along the shore of Lake Vesijärvi began to be transformed into the new Ankkuri district with its lakeside streets. The Sibelius Hall on the harbour includes parts of a century-old factory building. Around this concert and congress centre, a park of wooden architecture is being constructed. Also the former Mallasjuoma brewery building in the city centre is today used for cultural purposes, serving as the Art Brewery.