Vestas, Arla Foods, Salling Group, and Jysk have their headquarters there. Etymology The name originates from the city's location at the mouth of (Aarhus River). It is a compound of the two words , genitive of ("river", Modern Danish ), and ("mouth", in Modern Icelandic this word, spelt , is still used for "river delta"). In Valdemar's Census Book (1231) the city was called Arus, and in Icelandic it was known as , later written as Aars. Spelling The spelling "Aarhus" is first found in 1406 and gradually became the norm in the 17th century. With the Danish spelling reform of 1948, "Aa" was changed to "Å". Some Danish cities resisted the change but Aarhus city council opted to change the name. In 2010, the city council voted to change the name back from to again with effect from 1 January 2011. It is still grammatically correct to write geographical names with the letter Å and local councils are allowed to use the Aa spelling as an alternative and most newspapers and public institutions will accept either. Some official authorities such as the Danish Language Committee, publisher of the Danish Orthographic Dictionary, still retain as the main name, providing as a second option, in brackets and some institutions are still using explicitly in their official name, such as the local newspaper and the schools and . "Aa" was used by some major institutions between 1948 and 2011 as well, such as Aarhus University or the largest local sports club, (AGF), which has never used the "Å"-spelling. Certain geographically affiliated names have been updated to reflect the name of the city, such as the Aarhus River, changed from to . History Early history Founded in the early Viking Age, Aarhus is one of the oldest cities in Denmark, along with Ribe and Hedeby. The original Aros settlement was situated on the northern shores of a fjord by the mouth of the Aarhus River, right where the city center is today. It quickly became a hub for sea-going trade due to its position on intersecting trade routes in the Danish straits and the fertile countryside. The trade, however, was not nearly as prominent as that in Ribe and Hedeby during the Viking Age, and it was primarily linked to Norway as evidenced by archaeological finds. A shipbuilding yard from the Viking Age was uncovered upriver in 2002 by archaeologists. It was located