If you'd like to absorb the fascinating history of your new surroundings, head over to Old Stock Exchange.
You're spoiled for sightseeing choice when spending time in Lille Centre Ville. Old Stock Exchange is a good place to kick off here, but there are plenty of other worthy sights to consider. Lille Grand Square, Rihour Square, and Citadel of Lille are near the historic landmark and will round out your day nicely.