In 750, Archbishop Tilpin installed a community of Benedictine monks to guide pilgrims to the relics of Saint Remi. Thus began a monastic life that lasted a thousand years. Different successive abbots undertook many expansions and enrichment works which made the present Basilica of Saint-Remi gradually take shape. Of these changes over several centuries, the building retained various influences, from Romanesque to Renaissance through the Gothic movement. Listed as a UNESCO World Heritage Site, Saint-Remi Basilica is a collection of history and art which should not be missed. The 11th century Romanesque nave was lengthened by two transepts at the end of the 12th century to render it accessible to a greater number of pilgrims. At the same time, the facade was reconstructed, while a choir ambulatory and radiating chapels were created. While the Gothic style is apparent in these transformations, they in no way altered the homogeneity and serenity of the church. It contains Saint Remi's tomb, a collection of 12th century stained-glass windows and a Cattiaux grand organ, inaugurated in the year 2000. Saint-Remi was a great fortified monastery going back the 4th and 5th-centuries that held the Saint-Ampoule – with the unction used in the coronations of the Kings of France and the burial place of Saint-Remi. The old galleried nave with its wooden roof is thought to resemble that of many similar great churches in the North including, for example, Jumièges. The chevet figures importantly in the story of early gothic architecture. The delicacy of the slender columns refers to Suger's chevet at Saint Denis.
In 1005 the Abbot Aviard undertook the task to rebuild the church of St-Remy, and for twenty years the work went on uninterrupted before the vaulting collapsed, no doubt from insufficient buttressing. Abbot Theodoric erected the magnificent surviving basilica which Pope Leo IX dedicated in 1049 and to which he granted many privileges. The abbey library and its schools were of such high repute that Pope Alexander III wrote a commendatory letter to the Abbot Peter, which survives. During WWI the basilica was hit directly by German artillery. The process of rebuilding the basilica required new stained glass windows. Most of the stained glass was destroyed during WWI, the remaining ones are the windows of the second and third levels, the rose window behind the choir (the North Rose Window) and five more windows across from the choir.