Helsinki centres on the white Lutheran Cathedral above the harbour, the Suomenlinna sea-fortress on its UNESCO islands, and a sauna culture from the public Allas Sea Pool to Löyly's smoke-sauna on the Baltic shore.
Midsummer (Juhannus) emptys the city to lakeside cottages, Flow Festival mid-August at Suvilahti, and 19 hours of daylight stretch terrace season at Esplanadi.
Vappu May Day fills Senate Square with sparkling wine and student caps, Töölönlahti park reopening, and the Suomenlinna ferry running summer schedules.
Helsinki Design Week early September, Baltic herring market in early October at Market Square, and the Northern Lights season opens on dark nights at Nuuksio.
Christmas market on Senate Square, Lux Helsinki light festival the first week of January, and saunas at Löyly and Allas keep harbour swimming year-round.