The Aÿ-Champagne vineyard, classified as a Grand Cru, is also listed as a Unesco World Heritage Site, under the name « Coteaux, maisons et caves de Champagne ». At its heart, the Cité du Champagne Collet-Cogevi intends to showcase a unique expertise and terroir. The Collet Champagnes rest in the chalk and brick galleries, dug in 1880 35 metres underground. Stacked flat on top of each other, the vintage bottles mature on their lees out of sight and out of mind, for at least four years.