Mainz was founded in 13 BC as Moguntiacum by Roman soldiers.
Johannes Gutenberg was born in Mainz.
Mainz was a centre in the christianisation of the German and Slavic people. Beginning with Willigis (975-1011) until the end of the Holy Roman Empire the Archbishops of Mainz were archchancellors of the Empire and the most important of the seven Electors who elected the German King. Apart from Rome, Mainz is the only diocese in the world whose episcopal see is called a Holy See (sancta sedes). The Archbishops of Mainz traditionally were primas germaniae, the substitutes of the Pope north of the Alps. In 2001 the current Bishop of Mainz Karl Lehmann was appointed a Cardinal by Pope John Paul II.
The old importance of Mainz as an episcopal city is reflected in today's title of Cardinal Lehmann: His Eminence Karl Cardinal Lehmann, Cardinal-Priest of the Holy Roman Church, By the grace of God and the mercy of the Holy Roman See, Bishop of the Holy See of Mainz
Mainz is famous for its "Mainzer Fastnacht", a large party (Mardi Gras) which reaches its climax at "Rose Monday" when many of the citizens and tourists (approx. 500,000) are celebrating the beginning of Lent.
Mainz' downtown was heavily damaged in World War II.