Burial mounds have been found in all parts of the archipelago, on islands of various size. However, most barrows have originally been built on larger islands, which have later become even bigger due to the land uplift. Often the burial sites have been chosen so that they stand out from the surrounding landscape, such as rocky hills or tops of the islands, with a view to the sea. The burial mounds in Archipelago National Park are low and quite small heaps of stones, which have been built near the highest place of the islands, but not on the very top. Some graves are near the shore, and some are organised in groups of several cairns. Most of the burial mounds in Southwestern Archipelago, if not all of them, are from the Iron Age. Inside the cooperation area of Archipelago National Park, most graves have been found on the large islands of Nötö and Hitis. Already in the Iron Age, these areas bristled with islands, from which it was not a long way to go fishing or seal hunting in the outer archipelago. This area, with its favourable natural conditions, may well have been inhabited already in the Iron Age.