ONE May day in 2009, in the morning, I walked outside the door of the Albrecht Dürer Haus in Nuremberg. The date was of no particular importance, but while wandering around this part of the old city, I felt as though I was entering some gates of history. Not entirely clear, but not entirely odd.

A little to the north, the towers of Keizerburg Castle penetrated the expanse of sky. The castle was built in 1140 to immortalize the glory of king