A fortress was first established there in 1072, with the present keep being built in the 14th century. In the Middle Ages the whole peninsula was known as "the castle" and was enclosed by a wall. Parts of the wall can still be seen in the grounds of the Bailey colleges of Durham University and to the west of the Cathedral; these walls are Grade I listed. Along the inside of the wall on the east side ran a street. This road still exists and forms the present North and South Bailey. At its southern end, the street is still cobbled and is widely regarded as among the most attractive streets in the city. The central and southern parts of The Bailey, including the Castle, the Cathedral, the College, and Prebends Bridge, are now designated a World Heritage Site.