You know who guards the three million-piece art collection housed by St. Petersburg’s Hermitage Museum? Cats. Sixty-five of them, to be exact. Apparently the institution has employed stray felines to fend off rats and mice since 1745, though few visitors see the furry army (they’re restricted to the basement). One of their full-time caretakers (there are three) told CBS, “They’re not just mascots, they’re really employees of the Hermitage and they play a very important role.” Indeed.