The history of Herttoniemi Manor dates back to the 16th century. The Herttoniemi area is probably named after Laurens Hertoghe who might have been the first owner of the manor. The heyday was in the late 1700’s, when the manor was owned by Augustin Ehrensvärd. He led the construction of Suomenlinna fortress.
The present main building originates from the beginning of 19th century, when the manor was owned by admiral Carl Olof Cronstedt. The old porcelain factory was changed as the new main building and the park was established around it.
Today Herttoniemi park is an artistically unique milieu. The combination of baroque and English garden is one of the greatest in Finland. The main building functions as a manor museum and the park is open to the public. There is also an old old farm brought from Sipoo which is an outdoor museum.
Trullhalsar is a very well-preserved and restored burial field dating back to the Roman Iron Ages (0-400 AD) and Vendel period (550-800 AD). There are over 340 different kind of graves like round stones (called judgement rings), ship settings, tumuli and a viking-age picture stone (700 AD).
There are 291 graves of this type within the Trullhalsar burial ground, which occurs there in different sizes from two to eight metres in diameter and heights between 20 and 40 centimetres. Some of them still have a rounded stone in the centre as a so-called grave ball, a special feature of Scandinavian graves from the late Iron and Viking Age.
In addition, there is a ship setting, 26 stone circles and 31 menhirs within the burial ground, which measures about 200 x 150 metres. The stone circles, also called judge's rings, have diameters between four and 15 metres. They consist partly of lying boulders and partly of vertically placed stones. About half of them have a central stone in the centre of the circle.
From 1915 to 1916, many of the graves were archaeologically examined and both graves of men and women were found. The women's graves in particular suggest that the deceased were very wealthy during their lifetime. Jewellery and weapons or food were found, and in some graves even bones of lynxes and bears. Since these animals have never been found in the wild on Gotland, it is assumed that the deceased were given the skins of these animals in their graves.