Suomenlinna (
Finnish) or
Sveaborg (
Swedish), until 1918
Viapori (
Finnish), is an inhabited sea
fortress built on six islands (Kustaanmiekka, Susisaari, Iso-Mustasaari, Pikku-Mustasaari, Länsi-Mustasaari and Långören) and which now forms part of the city of
Helsinki, the
capital of
Finland.