The Diocese of Mainz, historically known in English as Mentz as well as by its French name Mayence, is a Latin Church ecclesiastical territory or diocese of the Catholic Church in Germany. It was founded in 304, promoted in 780 to Metropolitan Archbishopric of Mainz and demoted back in 1802 to bishopric. The diocese is suffragan diocese in the ecclesiastical province of the metropolitan Archdiocese of Freiburg. Its district is located in the states of Rhineland-Palatinate and Hesse. The seat of the diocese is in Mainz at the Cathedral dedicated to Saints Martin and Stephen. History Established in 340 as Diocese of Mainz Gained territory in 755 from the suppressed Diocese of Erfurt Promoted in 780 as Metropolitan Archdiocese of Mainz Demoted (back) on the 29th of November, 1801 to Diocese of Mainz (gained territory from Diocese of Metz, Diocese of Speyer, Metropolitan Archdiocese of Trier and Diocese of Worms) Lost territories repeatedly; in April 1818 to Diocese of Konstanz, Diocese of Speyer and Diocese of Wurzburg; in July 1821 to Diocese of Paderborn; in August 1821 to Diocese of Fulda and to establish Diocese of Limburg, and exchanged territory with Diocese of Trier; in March 1824 to Diocese of Hildesheim. Organization, extent and statistics Under Article 14 of the Reichskonkordat of 1933, which remains in force, the determination of the bishop to head the episcopal see and the composition of the chapter are governed by the provisions of Baden Concordat of 1932. As per 2014, it pastorally served 749,583 Catholics (25.9% of 2,891,000 total) on 7,692 km² in 319 parishes, 504 priests (409 diocesan, 95 religious), 124 deacons, 447 lay religious (132 brothers, 315 sisters), 19 seminarians. It is divided into 20 deaneries, which in turn are divided into 136 pastoral care units. In 2007 these parish associations or parish groups included all 335 parishes and other chaplaincies of the diocese (as of 2007). Pastoral units on the parish level have been introduced as a result of a profound structural change in the Catholic Church in Germany in many dioceses, the constitution of these units was determined by particular law [law of a particular region or territory], i.e., allowing for differences from one diocese to another. In the diocese of Mainz a parish group may be several parishes merged under the leadership of a single pastor. The parishes retain their church and state church legal personality. The pastor is