A fountain of sorts, the Miroir d'Eau is the world's largest reflecting pool. Covering an area of 3450 sq metres of black granite on the quayside opposite the imposing Palais de la Bourse, the 'water mirror' provides hours of entertainment on warm sunny days when the reflections in its thin slick of water – drained and refilled every half-hour –- are stunning. Every 23 minutes a dense fog-like vapour is ejected for three minutes to add to the fun (and photo opportunities).