Champagne Hillsides, Houses and Cellars: Coteaux de Mareuil-sur-d'Aÿ is a UNESCO World Heritage Site in the Marne Valley comprising three historic villages—Hautvillers, Aÿ, and Mareuil-sur-Aÿ—that documents centuries of Champagne wine production through landscape, architecture, and underground cellars. The site was inscribed as a UNESCO World Heritage Site in 2015 in ...