In the 11th century, Aire-sur-la-Lys was a Flemish town of about 1000 inhabitants. Life is organized around the castle and protected by powerful walls. Trade developed there, the city was pious, but the inhabitants had only a simple chapel to pray. They then decided to build a building which they said would be able to sing to the ears of God. In 1059, a collegiate church was finally built in this place. But soon, fire, wind and war came to attack the building. Defying the assaults of time and the madness of men, the collegiate church of Saint-Pierre, remnant of the past, remains for more than 8 centuries pointing its tower towards the sky of Aire-sur-la-Lys.