Osterberg is a named vineyard of the Alsace Grand Cru appellation in the commune of Ribeauville in Alsace, north-eastern France. It is one of three Grand Cru vineyards which sit above the northern side of Ribeauville, each occupying a distinct section of the hillside. Kirchberg is the highest and most westerly of the three, sitting just above the Geisberg site which sweeps from south to east around the apex of the hill. Osterberg occupies the eastern section, as its name ('East Hill') implies.
Osterberg is by far the largest of the trio, covering nearly 62 acres (24.6ha). It is also the most gentle, with its slopes rising steadily from the eastern end of modern Ribeauville (the old town is located to the west). The lowest Osterberg vines are located at an altitude of 820ft (250m) and climb to roughly 1150ft (350m). The site's perfect south-easterly aspect exposes the vines to gentle morning sunshine throughout the growing season, resulting in complex, delicately flavored wines. There is a perceptible difference between a Riesling from Osterberg and one from the hotter, more-exposed slopes of Kirchberg, just a few hundred meters away over the hillside.
The bedrock beneath Osterberg is composed of stratified marlstone and limestone formed in the Triassic and Jurassic periods respectively. This is covered by a thin layer of relatively free-draining soil made up of loose sandstone. There is also a significant clay component here, with good water-retention properties that often prove valuable in Alsace's characteristically dry climate.
The climate throughout Alsace is of continental type with particularly low rainfall – a result of the rain shadow cast by the Vosges. The mountains also provide protection from the prevailing westerly winds, making the Alsatian summer one of the driest and warmest in the northern half of France. At the other end of the temperature scale, the winters here are cold; it is not uncommon to see Alsace vineyards lined with snow.
Apart from a few notable exceptions, all Alsace Grand Cru wines are varietals and may be produced from Riesling, Gewurztraminer, Pinot Gris or Muscat. Geisberg is planted with a mix of the first three, but very little Muscat; this is not unusual for an Alsace Grand Cru vineyard.