The Cluny Abbey, also known as the Benedictine Abbey of Saint-Pierre de Cluny, is a former Benedictine monastery located in Cluny, Saône-et-Loire, France. It was founded in 910 AD by William I, Duke of Aquitaine, and was one of the most powerful and influential monasteries in Europe during the Middle Ages. The abbey reached its peak of prosperity in the 11th and 12th centuries, and was the center of a Benedictine reform movement that spread across Europe.

The Cluny Abbey was built in a unique architectural style that became known as "Cluniac", characterized by large and spacious naves, a centralized plan, and ribbed vaults. Its church, the largest in Europe at the time, was burned down in the late 18th century during the French Revolution. Today, only a small portion of the original complex remains, including the Chapter House, the refectory, and the dormitory.

The Cluny Abbey is considered one of the most important examples of medieval architecture, and its influence can be seen in many other religious buildings in Europe. It is also a testament to the power and wealth of the medieval church, and to the role of monasteries as centers of learning, culture, and social and economic power.