Malaren, Sweden's third-largest lake, meets the Baltic Sea in the heart of Stockholm, a strategic stop on the trade routes between the continent and the interior of Sweden. Ever since the first settlers staked out their positions here, over a thousand years ago, the Malaren valley has remained the cultural heartland of the country. The area is particularly rich in palaces because of its proximity to Stockholm; the palatial building-boom along the shores of Malaren reached its peak in the 17th and 18th centuries.