This is the work of Sébastien Leprestre, Marqui of Vauban, carried out on the order of Louis XIV, who had just conquered the town. Its construction lasted from 1667 until 1670. It was really a little town surrounded by five bastions in the form of a star with a total circumference of 2,200 metres. Building it called for the firing of 60 million bricks, and the quarrying of three million stone blocks and 70 000 pieces of sandstone. The royal entrance gate carries a Latin inscription sounding the praise of the glorious Sun King. The "Queen of Citadels" on the frontier of Flanders, formed part of a double line of strongholds between Gravelines, Dunkirk and Maubeuge/Rocroi. This was the famous "Pré Carré" conceived by Vauban to include 28 fortified towns.