Helsinki is by far the most populous urban area in Finland as well as the country's most important center for politics, education, finance, culture, and research.
More about Helsinki.
Helsinki has excellent public transportation throughout the city. The buses, trams and the metro are easily accessible and operate nearly around the clock. (NB: If you're planning to use public transportation a lot, a travel card will be more cost-efficient than single tickets).
Information on tickets, routes and locations.