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 it had a profound effect on natural killer cells (NKCs). "A. flos-aquae" triggers the movement of 40% of the circulating NKCs from the blood to tissues. Some compressed tablets of powdered "A. flos-aquae" cyanobacteria (named as "blue green algae") have been sold as food supplements, notably those filtered from Upper Klamath Lake in Oregon. Aphanizomenon flos-aquae Aphanizomenon flos-aquae is a brackish and freshwater species of cyanobacteria found around the world, including the Baltic Sea and the Great Lakes. "Aphanizomenon flos-aquae" can form dense surface aggregations in freshwater (known as "cyanobacterial blooms"). These blooms occur in areas of high nutrient loading,