Les Halles used to be Paris' underbelly. Nowadays, the former food market is the city's largest shopping centre, with the Forum des Halles, which is undergoing renovation work until 2016. You are bound to pass through on your way to the Centre Georges Pompidou and National Museum of Modern Art; along with Beaubourg, Les Halles makes for a lively and contrasting quarter: historical little streets and beautiful churches, including the huge Saint-Eustache, rub shoulders with modern art, gargoyles and secondhand-clothes shops.