Most important, a museum that is dedicated to a better understanding of the past does not have to look old or mimic the architecture of the period it memorializes. We are regularly delighted by the modern homes of old things - like the new Barnes, in which a historic institution has been re-presented in a compelling, contemporary way. Indeed, imitating historic buildings in a place like Philadelphia, which is so richly endowed with real ones, is like humming along at a concert, making it harder for the audience to hear the real music.