With letter and seal

Archbishop Adalbert (r. 1111-1137) granted the citizens of Mainz freedoms in court and taxation. This was the first time that the right to use the civic seal was given. This right symbolizes the emancipation of the citizens from their archepiscopal city lord by representing themselves as their own legal community. As one of the oldest city seals ever, the first Mainz seal shows St. Martin, the patron saint of the city, surrounded by walls and towers. The inscription praises the city as "Aurea Magontia" and as a "special daughter of the Roman Church".

Later, Gothic seals show the unique depiction of St. Martin asleep and dreaming of sharing his coat, as well as, for the first time, the Mainz double wheel, which from then on represented the city's coat of arms.