Around 800 Esslingen became a market town, its market rights being certified in 866. In 949–953 it was a possession of Liudolf, Duke of Swabia. Esslingen received city rights in 1229 under Emperor Frederick II. During the same period the still-extant Neckar bridge was built, making Esslingen a major center for trade on the route between Italy, Switzerland, and northern Germany. Taxes provided by the bridge and market led to further growth of the town, as did the export of the highly regarded wines from the region.