Calleva Atrebatum road divided into routes to various other points west, including the road to Aquae Sulis (Bath); Ermin Way to Glevum (Gloucester); and the Port Way to Sorviodunum (Old Sarum near modern Salisbury). The earthworks and, for much of the circumference, the ruined walls are still visible. The remains of the amphitheatre, added about AD 70-80 and situated outside the city walls, can also be clearly seen. The area inside the walls is now largely farmland with no visible distinguishing features, other than the enclosing earthworks and walls, with a tiny mediaeval church in one corner. There is a spring that
Aphanizomenon flos-aquae toxic chemicals released when cells die. Once released (lysed), and ingested, these toxins can damage liver and nerve tissues in mammals. In areas where water quality is not closely monitored, the World Health Organization has assessed toxic algae as a health risk, citing the production of anatoxin-a, saxitoxins, and cylindrospermopsin. Dogs have been reported to have become ill or have fatal reactions after swimming in rivers and lakes containing toxic "A. flos-aquae". Microcystin toxin has been found in all 16 samples of "A. flos-aquae" products sold as food supplements in Germany and Switzerland, originating from Lake Klamath: 10 of 16