The Dannemora mine was one of the most important iron ore mines in Sweden. The mine was closed by its owners SSAB in 1992. It may have been open since the 13th century, but the first documentary reference was in 1481.
The mine supplied all the ironworks making oregrounds iron by the Walloon process (using a blast furnace and finery forge), such as Österby and Lövsta. Their products were particularly pure iron, due the manganese content of the iron ore. This made it the best material for conversion to blister steel, the main variety of steel made in Great Britain between the 1610s and the 1850s. The mine has a depth of 640 metres.
Today the area is both a historic site and mining technology museum. There are a souvenir shop, a craftshop, an atique store and a mineral museum. Visitors may stroll along the various open cast mines, the pits have vertical walls and look pretty impressive. There are some 50 open cast mines, fantastic abysses made the mine field a popular attraction for painters, writers and royalty from many countries during the 19th century. Carl von Linné visited the mines, and there are numerous historic paintings, in oil and copper engravings.
Storrymmningen is the longest open cast mine in th field, more than 200m long and 100m deep. It is visited on guided tours, which then enter the underground mine and show the main shaft going down to the 620m level. The tour ends at a small mchine house nearby, which contains the first steam engine of Sweden, which was used between 1728 and 1735 to power the water pumps of the mine.
References:The ancient Argos Theater was built in 320 BC. and is located in Argos, Greece against Larissa Hill. Nearby from this site is Agora, Roman Odeon, and the Baths of Argos. The theater is one of the largest architectural developments in Greece and was renovated in ca 120 AD.
The Hellenistic theater at Argos is cut into the hillside of the Larisa, with 90 steps up a steep incline, forming a narrow rectilinear cavea. Among the largest theaters in Greece, it held about 20,000 spectators and is divided by two landings into three horizontal sections. Staircases further divide the cavea into four cunei, corresponding to the tribes of Argos A high wall was erected to prevent unauthorized access into the theatron and may have helped the acoustics, but it is said the sound quality is still very good today.
Around 120 CE, both theaters were renovated in the Roman style.