The Médoc was a marsh before it was a vineyard. Dutch engineers drained it in the seventeenth century, cutting drainage channels — the jalles — through waterlogged ground on the left bank of the Gironde estuary. What emerged was gravel: deep beds of quartz and flint washed down from the Pyrenees and the Massif Central during glacial melt. Gravel drains fast, radiates stored heat at night, and forces vine roots deep. Cabernet Sauvignon, a late-ripening variety that struggles elsewhere in France, found its precise habitat. The hierarchy that still governs the region was fixed in a single document. For the 1855 Paris Exposition Universelle, Napoleon III asked Bordeaux brokers to rank the region's wines; they ranked by price, producing five growths across sixty-one châteaux. Only one estate has been promoted since — Mouton Rothschild, in 1973. Nearly every itinerary on a medoc wine tour from bordeaux traces that list northward: Margaux, Saint-Julien, Pauillac, Saint-Estèphe, four appellations strung along the D2, the Route des Châteaux. The architecture reflects the money the classification created. Château Margaux stands behind a neoclassical colonnade completed in 1815 by Louis Combes. Château Pichon Longueville presents turrets and a reflecting pool. Cos d'Estournel, in Saint-Estèphe, carries carved pagodas and a Zanzibar door — the folly of a nineteenth-century merchant who exported claret to India. Newer cellars answer the old ones in concrete and glass. The barrel halls beneath them hold French oak, roughly half of it new each vintage, where wines rest eighteen to twenty-four months before bottling. Modern practice has shifted. Optical sorting tables now reject imperfect berries at reception. Parcel-by-parcel vinification in smaller vats has replaced the blunt tank sizes of the 1970s. Warmer growing seasons have moved harvest earlier, and Merlot's share in some blends has been trimmed to preserve freshness. The Médoc remains overwhelmingly a blending region: Cabernet Sauvignon leads, Merlot softens, Cabernet Franc and Petit Verdot add lift and structure. Distance shapes access. Margaux sits roughly 30 kilometres from Bordeaux city centre; Pauillac closer to 50. Most estates receive visitors by appointment only, which is why organised Bordeaux Médoc château tours dominate. Half-day formats concentrate on Margaux and its neighbours; a full-day medoc wine tour from bordeaux reaches the northern appellations and pairs cellar visits with gourmet tastings. Entry to the region itself costs 0 EUR — the vineyards are public road and open horizon. The cellars, and the classified bottles inside them, are another matter entirely.