Cluny III, Romanesque abbey in Cluny, France

Cluny III was the third major church of the monastery and stood unmatched in scale and architectural ambition in the medieval world. The building featured multiple towers, rounded arches, and was part of a sprawling monastic complex with numerous connected structures.

Construction began in 1088 under Abbot Hugh and produced a building that held the distinction of being the largest church in Christian Europe for generations. Only the construction of Saint Peter's Basilica in Rome would eventually surpass it.

The monastery became a center of spiritual authority that shaped religious life across Western Europe for centuries. Pilgrims traveled from distant lands to visit this revered place of faith and learning.

Of the church, the south arm of the great transept with the octagonal Clocher de l'Eau bénite (31 m) and part of the small transept survive; the rest is marked in the town fabric. Fragments of the portal and sculpture are held at the Musée Ochier in Cluny and the Musée du Palais Jean de Bourbon, and a metal-framed remounting of the portal is displayed there. Allow time to walk between the surviving masonry and the museums.

Only a few remains of the once-mighty structure are visible today, including a transept and several walls that hint at its original grandeur. Modern technology allows visitors to see the lost architecture come alive again through projections and digital models.