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.