Glastonbury was never a real island, but it was surrounded on most sides by water. It was still connected to the mainland by a narrow strip of land (the current route of the road leading to Shepton Mallet). This approach to Glastonbury features an erthwork, which was either a defensive barrier, or a symbolic barrier marking the entrance to a sacred site. Opinions differ. It is still visible just past West Pennard heading towards Glastonbury, and is know as Ponter's Ball.