Samuel Ball Platner, A Topographical Dictionary of Ancient Rome, London: Oxford University Press, 1929.

Because of Augustus, there were 14 regions in the city of Rome compared to its previous 4. This division into fourteen regions continued in force until the sevent century when an ecclesiastical division into seven regions was introduced and opened the way for the entirely different organization of the Middle Ages.

II, CAELIMONTIUM: * the name given to Region II in Reg., and in one inscription (CIL xv.7190). It included the greater part of the Caelian hill and extended east to the Aurelian wall. This word, Caelimontium, is evidently analogous in formation to Septimontium, and may have been used as the name of the region because it included the hill, or the region may have been so called because Caelimontium was one of its principal streets (cf. Alta Semita). Some evidence for the latter hypothesis is found in the adjective Caelimontienses (CIL vi.31893, 31899), although it has been suggested (BC 1891, 353-354) that this may mean those who dwelt in a street or quarter that was called Caelimontium, a restricted use of the latter term which has parallels.