One of Finland's major winter-sports centres, Lahti is a modern town about 100km north of Helsinki. It's a good place to go if you're interested in skiing, with a good museum on the sport, alongside the city's frighteningly high ski jumps. Lahti has hosted several world championships, most recently in 2001.
Founded in 1905, the city isn't hugely interesting in other respects, and lacks anything that could be called an 'old town'. Most of the downtown area, in fact, consists of a series of linked shopping centres. The 10, 000 Karelian refugees who arrived after WWII have contributed their entrepreneurial spirit to what the locals call the 'Business City'. Lahti does make a good base for visiting nearby attractions. Its location by Vesijärvi (which is connected to Lake Päijänne) makes it the obvious place to start a ferry trip to Jyväskylä. One of the largest lakes in Finland, Päijänne provides Helsinki with tap water.