Germany's reputation as the greatest white-wine producing nation in the world was historically based largely on the Rheingau.
Today the supremacy of this very small region (7,744 acres/3,134 hectares) is challenged by wines from the Mosel and the Pfalz, yet the Rheingau has the longest history of quality winemaking of any region in Germany.
It is a serene, aristocratic region — one long, virtually continuous horizontal slope, a rolling carpet of vines, with the densely forested Taunus Mountains rising behind.
In a sense the mountains created the region: they abruptly halted the Rhine's northward flow and forced it west for 20 miles before it could resume, leaving a nearly ideal, immense south-facing bank backed by forests that block cold northern winds.
The leading grape is riesling — the first record of riesling planted in Germany dates from 1435 at Schloss Johannisberg, a former Benedictine abbey in the Rheingau — and of all German regions the Rheingau has the highest percentage of riesling, nearly 80 percent of its acreage.
The rieslings here are entirely different from Mosel rieslings: richer, rounder, earthier and more voluptuous.
Absent are the Mosel's icicle-like sharpness and slate flavours, and in their place is a near perfect gripping expression of lip-smacking fruit; the best have amazing breadth, suggesting everything from violets and cassis to apricots and honey.
Sun, soil and latitude make the difference — the Rheingau lies farther south than the Mosel, its south-facing bank rises gently from a river that acts as a giant sunlight reflector, and its soil is not solely slate but a vast mixture including loess, loam, limestone, marl, sand and quartzite.