Unplottable

From UnknowableWiki

An unplottable location is a place that cannot be mapped. Making places unplottable is presumably advanced magic, and there seem to be more than one option for making a place unplottable, e.g. allowing a given location to appear on wizard charts only, or none at all.

Hogwarts is probably unplottable; according to Hogwarts: A History, Muggles who visit it see only ruins with a sign noting that the building is dangerously unstable. The Marauders, however, were able to make a map of the school (PA10), listing most of its rooms, which is strong evidence against the castle's hypothetical unplottable status.

Two notable rooms not included on the Map are the Chamber of Secrets, which the Marauders could not access—in any case, it was perhaps made unplottable by its builder, Salazar Slytherin—, and the Room of Requirement. The latter effectively seems to be unplottable, as Hermione Granger notes one occasion (HBP21).

The stadium where the final of the 1994 Quidditch World Cup took place was also unplottable. The Ministry of Magic had extensive anti-Muggle protections in place as well (GF7).

Hermione suggests that Durmstrang and Beauxbatons may be unplottable to make them more difficult for other wizards to find (GF11).

The Blacks' house, located at number twelve, Grimmauld Place, is unplottable (OP6).

The Isle of Drear is unplottable to protect Muggles from its only inhabitants, Quintapeds (FBAZ).

The Ministry building is presumably unplottable as well, but there has been no indication of that fact in the series.