The two pit furnaces at Dunshammar, two kilometres south of Ängelsberg, constitute the oldest link in the 1,500 years during which iron has been produced in the region. The furnaces have been well preserved and the site is one of only a few where Iron-Age pit furnaces can be seen in their natural setting. Several other pit furnaces existed in the bays on the eastern shore of lake Åmänningen during the Iron Age. The people lived just back from the shore, and Iron-Age graves have been discovered near Västervåla church and at Virsbo, 8 km to the south.
The furnaces, made of stone and sealed with clay, were created in pits, and bellows were used to blow air into the furnace. The ore was brought up from the bottom of the lake using boats or rafts in the summer, and through holes made in the ice in winter. The ore from the bed of the lake was rich in iron, having a concentration of some 60%. However, it also contained phosphorus, which makes the iron hard and brittle. Once the iron had been brought up from the lake bed, it was roasted to remove the moisture and any organic material. When the bellows were operating, the temperature in the furnace reached about 1100°C. The slag ran down and settled out on the bottom of the furnace, while the iron solidified into a lump on top of the slag. Because of the relatively low temperature, the iron had a low carbon content and could be forged straight from the furnace. Most of the phosphorus was carried away in the slag.
Two archeological digs have taken place on the site, one in 1969–70, and the other in 1985. The age of the furnaces, determined by radiocarbon dating (C14), was found to be AD 300-800. An estimate was also made of the amount of iron produced over the centuries, and this turned out to be six or seven tonnes.
As well as the two well-preserved pit furnaces, there are also a charcoal-burning stack and three large slag heaps on the site. Around the furnaces are hollows that were created when clay was dug out for sealing the furnaces. The local heritage association at Västervåla has established a small museum in which the ancient process of producing iron is depicted in words and pictures.References:
Roman Walls of Lugo are an exceptional architectural, archaeological and constructive legacy of Roman engineering, dating from the 3rd and 4th centuries AD. The Walls are built of internal and external stone facings of slate with some granite, with a core filling of a conglomerate of slate slabs and worked stone pieces from Roman buildings, interlocked with lime mortar.
Their total length of 2117 m in the shape of an oblong rectangle occupies an area of 1.68 ha. Their height varies between 8 and 10 m, with a width of 4.2 m, reaching 7 m in some specific points. The walls still contain 85 external towers, 10 gates (five of which are original and five that were opened in modern times), four staircases and two ramps providing access to the walkway along the top of the walls, one of which is internal and the other external. Each tower contained access stairs leading from the intervallum to the wall walk of town wall, of which a total of 21 have been discovered to date.
The defences of Lugo are the most complete and best preserved example of Roman military architecture in the Western Roman Empire.
Despite the renovation work carried out, the walls conserve their original layout and the construction features associated with their defensive purpose, with walls, battlements, towers, fortifications, both modern and original gates and stairways, and a moat.
Since they were built, the walls have defined the layout and growth of the city, which was declared a Historical-Artistic Ensemble in 1973, forming a part of it and becoming an emblematic structure that can be freely accessed to walk along. The local inhabitants and visitors alike have used them as an area for enjoyment and as a part of urban life for centuries.
The fortifications were added to UNESCO"s World Heritage List in late 2000 and are a popular tourist attraction.