Kaiserburg Nuremberg

Dear Friends
the visit of Nuremberg cannot be considered complete without the visit of the Middle-age Kaiserburg of the town:
http://www.schloesser.bayern.de/deutsch/schloss/objekte/nbg_burg.htm .
It represent one of the most powerful and imposing fortress of the German Holy Roman Empire: http://en.wikipedia.org/wiki/Holy_Roman_Empire .
One remarkable architectural feature of the Kaiserburg is that its wall includes portions of the original hill cliff on which it was built and to which Nuremberg owes its name (nor = rocky hill). Any comment from your side is welcomed.
Salutations
Giancarlo