Bath city walls the Romans, to surround their town (known then as "Aquae Sulis"), probably in the 3rd century. The Anglo-Saxons by the 10th century had established Bath as a fortified "burh" (borough), utilising the existing town walls, and maintaining Bath as a centre of regional power. Bath, located on the northern edge of the kingdom of Wessex, would have guarded against any attack from neighbouring Mercia, which was held by the Danes for a time. The height of the walls was increased on the orders of King Stephen during The Anarchy. Bath's medieval walls included four gates. The North and South Gates
Aphanizomenon flos-aquae (dietary supplement) This linked article is about a single strain of AFA labeled as toxic that has been reclassified. Colony-forming morphology is one of the characteristics of the species "Aphanizomenon flos-aquae"; conversely "Aphanizomenon" are not known to form colonies. Algologists Li and Carmichael noted colony formation, or lack thereof, and other morphologic distinctions when comparing "Aphanizomenon flos-aquae" with "Aphanizomenon". Their genetic comparison of "Aphanizomenon flos-aquae" to other species in the genus "Aphanizomenon" indicates dissimilarity between "Aphanizomenon flos-aquae" and "Aphanizomenon" species. Cyanobacteria have been a staple in the diets of many cultures and have been used for both food and commerce by indigenous