One of Sweden’s first real towns. During Viking times, Birka on the island of Björkö in Lake Mälaren, was the central hub and the most important marketplace in the entire Mälar Valley. It was established in the eighth century, attracting travelers from near and afar. Birka of today has a wealth of ancient remains that have been excavated and studied since the 19th century. Birka is ideal for a daytrip. During summer, boats depart from the dock at City hall.