Metz Cathedral is the cathedral of the Catholic Diocese of Metz, the seat of the bishops of Metz. It is dedicated to Saint Stephen. The diocese dates back at least to the 4th century and the present cathedral building was begun in the early 14th century. In the mid-14th century, it was joined to the collegiate church of Notre-Dame, and given a new transept and l…Metz Cathedral is the cathedral of the Catholic Diocese of Metz, the seat of the bishops of Metz. It is dedicated to Saint Stephen. The diocese dates back at least to the 4th century and the present cathedral building was begun in the early 14th century. In the mid-14th century, it was joined to the collegiate church of Notre-Dame, and given a new transept and late Gothic chevet, finished between 1486 and 1520. The cathedral treasury displays a rich collection assembled over the long centuries of the history of the Metz diocese and include sacred vestments and items used for the Eucharist.