User blog comment:MakeShift/More promo images/@comment-1418842-20121130102855/@comment-5574752-20130908112543

It's most likely that they are a real city (probably one in Canada). Their budget is not the largest for a television show, so it would be stretching their pockets to CGI the entire city. They probably superimpose images on the already existing building and maybe one or two are really CGI.