Until 1979, it was believed that Skien was founded in the 14th century. However, the archaeological find of a carving of the Skien animal has established its founding to before 1000 A.D. The city was then a meeting place for inland farmers and sailing traders, and also as a shipping harbour for whetstones from Eidsborg (inland Telemark). The settlement can be traced back to the 11th century, and Gims�y Abbey was founded in the 12th century. Skien was given formal commercial town rights by the Danish crown in 1358. Timber has historically been the most dominant export product from Skien, and the city was the Kingdom's leading port town for shipping timber from the 16th century onwards. The oldest remaining building is Gjerpen church (built in approximately 1150).
From the 16th century, the city came to be dominated by a group of families known as patricians. In an 1882 letter to Georg Brandes, Henrik Ibsen mentions the families Paus, Plesner, von der Lippe, Cappelen and Blom as the most prominent patrician families when he grew up there.
The current town layout was fixed after the last town fire in 1886. In 1964, the rural municipalities Solum and Gjerpen were merged with Skien town, forming the Skien municipality
