The building of these fortification walls may have become an area of contest, at least between the three main colonies. However, the lack of fortifications around smaller villas leads scholars to believe that there was no real threat of peasant revolt at this time even if it was on the mind of Roman elites. The purpose of the walls remain unclear. The towns would have needed a valid reason to convince the Emperor to allow them the resources and manpower to build because they were not simple projects. Emperors seemed concerned that if these towns were surprisingly overtaken by a peasant revolt that the fortifications could be used against the Romans. Although the villas mentioned above may not have been heavily fortified there is archeological evidence to suggest a period of intense building to expand the infrastructure of villas around the Upper Province. For example, two villas on the outer ridge of the Cotswolds called Witcombe and Frocester Court were enlarged between 270-275 AD. It is also thought that the Emperor Probus made sure to fortify coastal dwellings within the province. This was done in tandem with sea fortifications in Gaul to guarantee a safer hold on the English Channel. Londinium Due to the lack of minted coins in Roman Britain during part of the Severan period (180–253 CE), it is hard for scholars to tell whether Upper Britain as a whole province was in a period of decline or not, even though there is much evidence towards a decline in Londinium. It is clearly known that there was at least enough money and resources to complete a new wall of Londinium during this period. The discovery of a coin containing the image of Commodus at a London site leads historians to believe that the wall was not completed no earlier than 190 CE, and perhaps as late as 220 CE. The new wall was 9 ft (2.7m) thick at ground level, including an 8 ft (2.4m)-thick plinth above. The work was beyond local capability at the time which meant that the order to build it must have come from the top of the Roman Empire. The wall was either commissioned by Albinus or Severus. To tell which leader built the wall, both of their motivations have been studied by historians. City walls served as a main protector against enemies, but most towns in Britain did not receive much fortification