What the experts say: 'Neither Botticelli's "Chart of Hell" nor GPS enable users to be 100% certain of their real-time whereabouts in the underworld. Would-be sponsored rollerbladers who do lose their way should therefore rule out salvation from the US Calvary and ask the sodomites in the inner ring of Circle 7 or the thieves chased by venomous snakes in Ditch 7 of Circle 8 for directions to the nearest exit'