Vauban's "queen of citadels" is the model for the military constructions that dot France. The Lille Citadelle was built between 1668 and 1671 at the request of Louis XIV, to designs by military engineer and architect Sébastien Le Prestre de Vauban. He conceived his fortress as a response to changes in the art of warfare. Although it has lost its original function, its rigor and formal simplicity have made it a source of inspiration for great contemporary architects.