The Bir­ka archae­o­log­i­cal site is locat­ed on Bjorko Island in Lake Malar and was occu­pied in the 9th and 10th cen­turies. Hov­gar­den is sit­u­at­ed on the neigh­bour­ing island of Adel­so. Togeth­er, they make up an archae­o­log­i­cal com­plex which illus­trates the elab­o­rate trad­ing net­works of Viking-Age Europe and their influ­ence on the sub­se­quent his­to­ry of Scan­di­navia. Bir­ka was also impor­tant as the site of the first Chris­t­ian con­gre­ga­tion in Swe­den, found­ed in 831 by St Ans­gar.