Osterberg became part of the other Grands Crus in 1992, but it was already mentioned in documents dating back to the Middle Ages and the Lords of Ribeaupierre owned their vineyards. In regards to Ribeauvillé, Michel Mastrojanni points out:
Imperial town, former fiefdom of the powerful Ribeaupierre family which dominating it during the 13th century up until the Revolution (by also planting numerous vineyards in the region, from Ammerschwihr to Rodern), the Fiddlers’ town was bestowed many privileges and benefited from continuous wine-making prosperity.
Michel Mastrojanni, Le grand livre des vins d’Alsace, Solar, 1993, p. 82
The same author can also be thanked for telling the history of the Clos du Zahnacker:
This illustrious clos, which today belongs to the cooperative wine-making cellar, was initially owned by the Benedictine abbey of Ribeauvillé. Tradition has it that during the 12th century, a certain Zahn, monk-knight, had brought back the best grape varieties from the Holy Land and had planted them here. In 1426, the German emperor Sigismond, wanting to be allied with King Eric, sovereign of Sweden, Norway and Denmark, had a barrel of Zahnacker wine transported by water until Lubeck and which the imperial ambassador then offered to the Nordic royal court. It is also Zahnacker wine – by then it was in the hands of Ribeauvillé lords – which was served to Louis XIV during his stay in Ribeauvillé in 1673, and this in a spectacular silver-gilt hanap, still visible today in the small city hall museum. The Clos never departed from its original identity: 120 years of pebbly marl, forming a triangle at mid-hill within the Osterberg, and complanted on either side with noble varietals (currently a third Riesling, Gewurztraminer and Pinot Gris).
Op.cit., p. 88
3>Beloved vineyards and land
This demanding terroir obliges wine-makers to limit production using different methods. The old, low-yielding vines are still numerous. There is rigorous pruning which allows to control the production potential.