The “belly of Paris” (Emile Zola) has undegone multiple transformations since the great days of the food market that started around 1100. Neatly delineated by the rue Beaubourg in the east, the rue du Louvre in the west, the northern rue Réaumur, and southern rue de Rivoli, Les Halles functioned as a market until 1969. The grocers and butchers were then moved out to the suburb of Rungis and their superb 1860s Baltard pavilions were demolished. It took the city council and government 10 years of wrangling to decide how to fill the gaping hole : although the result is aesthetically disastrous, Les Halles has recovered its role as a central commercial and social hub. Venture below ground into the Forum for shopping, cinemas, swimming…