In England, examples of reverence for wells and springs occur at a variety of historical periods. The medieval traveller William of Worcester saw a 'holy-hole, or well' within the cave at Wookey (Somerset), a site of human habitation in the Palaeolithic era and the source of a river which had been the site of ritual activity. The proximity of named springs to Neolithic or Iron Age monuments, such as the Swallowhead Springs, close to Silbury Hill (Wiltshire) or the Holy Well near Tadmarton Hill (Oxfordshire), suggests that reverence for such sites continued without a break. There is abundant evidence for the importance of wells and springs in the Roman and sub-Roman period, not just at temple complexes such as Bath (Somerset), Chedworth (Gloucestershire), and Blunsdon Ridge (Wiltshire) which have medicinal springs at their centre, but a variety of smaller sites, and at wells and ritual shafts used for superstitious and sub-religious rituals.