There’s an exhibit on the Emperor Constantine the Great, "York’s Roman Emperor," running until late October at the York Museum. Here’s a review of it from the European Journal of Archaeology, and here’s another review from the Bryn Mawr Classical Review. Alas, the $100 price for the exhibition catalog will probably deter all but the most committed Romano- or Constantinophiles. Let the exhibition close, give it 8 weeks, and see if some of the catalogs turn up at the on-line used bookstores.