"The most recent preserved example in the library is dated 1602, just before the Scottish Clearances," William told Ivarsson, pointing his wand at the scroll rack and summoning another storage tube to the table. "It's only half-finished, but I would judge it to be the most accurate. The castle shifts over time; most of the medieval and earlier Renaissance charts are more hindrance than help. Headmasters and -mistresses have changed the layout and use of particular rooms - there were four dueling halls at one time, as you can see here, but three of them now serve other purposes, and the celestial observatory marked here was struck by Dark lightning during the eighteen hundreds - and the rooms and corridors themselves have a tendency to relocate gradually over the years."
He wasn't sure how much he ought to divulge with regard to his own concerns about the library to a foreign agent, but it seemed only fair to inform her of what he did know about this particular collection. "I can tell you that there used to be three maps from the twentieth century, at least one of which was in excellent condition. It was used in an assignment when I was at school here." He glanced at the gaping holes in the rack of maps and charts, and the significantly lighter burden in one area in particular. "Some materials in the Hogwarts catalogue are currently missing, following the castle's occupation during the recent war. It seems those are among the items in question."