Work on the new cathedral building, the present Salisbury Cathedral, began in 1221. The site was supposedly established by shooting an arrow from Old Sarum, although this is certainly a legend: the distance is over . The legend is sometimes amended to claim that the arrow struck a white deer, which continued to run and died on the spot where the cathedral now rests. The structure was built upon wooden faggots on a gravel bed with unusually shallow foundations of and the main body was completed in only 38 years. The tall spire, the tallest in the UK, was built later. With royal approval, many of the stones for the new cathedral were taken from the old one; others came from Chilmark. They were probably transported by ox-cart, owing to the obstruction to boats on the River Nadder caused by its many weirs and watermills. The cathedral is considered a masterpiece of Early English architecture. The spire's large clock was installed in 1386, and is one of the oldest surviving mechanical clocks in the world. The Cathedral also contains the best-preserved of the four surviving copies of Magna Carta.