Various writers, in the course of the time, have called the provincial capital as Grossetum and others as Crassetum or Rosetum.

The most ancient and authentic writings are the Pops' bulls of Innocenzo II in 1138, Celestano II. in 1143 and Clemente III in 1188 which is indicated by its right name as Grossetum.
To complete the picture, we might add that the ancient inhabitants of Grosseto, in order to prove their Etruscan origin, assumed a griffon, the mythic winged animal already preferred by Etruscans as their emblem. Later on, they posed it above a red shield to signify the Ghibbeline party constantly followed by Grossetans.
In 1328, they armed it with a sword in order to remember the heroic defense of their town in September 1328 against Ludovico il Bavarro whose numerous army became withdrawn in just four days time.

"A strong city. Not a very large one, well walled and protected by six bastions and one fortress. With only two doors, one that looks at the mainland and the other one directed towards the sea."
In this way Repetti describes the city in its cartographic dictionary of Tuscany. There are many historical events that accompanied the growth of Grosseto from a village to a city.

The origins of Grosseto date back to the medieval era. However, the findings available are not sufficient enough to provide the certainty of its Etruscan or Roman origin.

In August 803, the Church of St. Giorgio and its assets were given to Ildebrando degli Aldobrandeschi whose successors became lords of Maremma until the end of XII century. This period signalled the beginning of "dominium" of Aldobrandeschi, thanks to whom the city reached its major power. It was a real dominium that in 1137 granted to its governance a lot of independence from the imperial vicars and thus the possibility to resist the attack of the German army lead by duke Arrigo di Baviera. A very important date is 1138, which is when the transfer of the Episcopal seat of Roselle to Grosseto took place. In 1151 the city took an oath in Siena, which stipulated the accord for the tax of the salt in the beginning of the XII century.