The notion of an Alsace Grand Cru was first proposed in 1975, but the first official Grand Cru vineyards did not emerge until 1983 when 25 vineyards were designated as such. In 1985 a further 25 more were declared and finally a 51st, Kaefferkopf, was added in 2006. Grand Cru AOC wines are single varietal wines from the four noble Alsatian grapes, although there are some notable exceptions. Altenberg de Bergheim and Kaefferkopf for example may blend according to certain proscribed proportions. In addition, Zotzenberg is a historical site for Sylvaner, and as such the grape is permitted in Grand Cru.