The third largest lake in Sweden (1 140km²), Mälaren stretches from west to east over 150km as far as Stockholm, where it flows into the Baltic. It is made up of a multitude of meandering arms separated by islands and peninsulas. Some 20 historical houses, ranging from sumptuous royal castles - Grönsö, Skokloster and Gripsholm Castles - to the most modest of mansions, grace the banks of Lake Mälaren as well as some of its islands. Among all these splendours, the site of Anundshög is especially remarkable.