The Bar à Vin is run by the Conseil Interprofessionnel du Vin de Bordeaux — the official body of the Bordeaux wine trade — on the ground floor of their building on the Cours du 30 Juillet. It is the most reliable place in the city to drink a proper range of Bordeaux wines at reasonable prices: around twenty appellations available by the glass, with a rotation that changes seasonally.
The atmosphere is pleasant and unfussy — a marble counter, knowledgeable but unpretentious staff, and a short menu of charcuterie, cheese, and tartines to accompany the wine. It is popular with a mix of tourists and professionals from the wine trade. Open Tuesday to Saturday, lunchtimes and afternoons. This is the best starting point if you want to understand the range of Bordeaux wines before committing to a more expensive bottle elsewhere.