Lincoln (ancient Lindum Colonia) is the administrative centre of Lincolnshire in the East of England, on the Witham River. Lincoln is the commercial and transportation centre for the surrounding agricultural region, with manufactures including machinery and electronic equipment. The city's most prominent structure is its cathedral, built between 1075 and 1501, a fine example of Gothic architecture. For one hundred and fifty years during the middle ages the building was the tallest in the world (beat that Petronas!). Also notable are Lincoln Castle (founded in 1068 by William the Conqueror), the medieval city gates and a museum with an extensive archaeological collection. The site of modern-day Lincoln, occupied in Celtic times, was taken by the Romans in AD47 and developed into an important settlement. In the 9th and 10th centuries it was a Danish borough, while the Middle Ages saw it flourish as a market town.