Birka, on the island of Björkö in present-day Sweden, was an important Viking Age trading center which handled goods from Scandinavia as well as many parts of the European continent and the Orient. Björkö is located in Lake Mälaren, 30 kilometers west of contemporary Stockholm, in the municipality of Ekerö.

Björkö is an island in Lake Mälaren in eastern-central Sweden. It is mostly famous for housing the excavation site Birka populated c. 750-975 CE, together with Hovgården on Adelsö declared a World Heritage Site in 1993. Located just south of Adelsö and west of Ekerö and Munsö islands, it is one of the islands in Ekerö Municipality.