Roselle was set in a favourable geographic position: it faced the south-cast side of the Prile "lake", which was a natural line of communication with the sea and the coastal towns, while the Ombrone river, by the mouth of which Roselle was located, made possible the trade with the Val d'Orcia and the towns of the internal Etruria. The earliest traces of occupation on Roselle go back to the Prehistoric and Protohistoric periods, but the organization of the settlement began by the first half of the 7th century B.C., probably due to a phenomenon of synecism which interested the communities of the surrounding territory. In the 7th century B.C., the choice of this area for a settlement was due to the large and fertile hinterland suited to agriculture, appropriate for the expectation of control over several lines of communication (landing place of the Prile "Lake", confluence of the Ombrone with the sea) and to the natural possibility of defence. Among the occasional literary sources on Roselle, it is worth referring to Dionysius of Alicarnassos, who mentions the city together with Chiusi, Arezzo and Volterra, as taking part in supporting the Latins against Tarquinius Priscus at the end of the 7th century B.C. This seems to imply that Roselle was a city of first-rate importance in the Orientalising period, since it was able to offer military forces as the other wealthy and thriving Etruscan sites, of elder foundation. The archaeological evidence fits this historical context: the remains of the eldest walls of Roselle, with foundations of regular blocks and built of dried clay bricks, date to the 7th century B.C. The "building with enclosure", lately interpreted as a religious place, dates to the Orientalising age and it lies in the valley between the two hills, where eventually the Roman forum was established. In the 6th century B.C. the city had a great development: by the last quarter of the 6th century B.C., in fact, Greek pottery imports show that the importance of Roselle was increasingly greatly. The second ring of city walls, built of polygonal blocks of sandstone, dated from the 6th century B.C., run all around both the hills, and it is still visible in extensive parts. At that time, the city was build in clay, terracottas and dry-walled stones. The two hills and the intermediate valley were widely urbanized, although they maintained - as we deduce from the archaeological surveys conducted until nowadays their own characteristics: private buildings were on the north hill, while the factories were concentrated on the south hill.

A continuity of life is documented during Classical and Hellenistic ages. On the south hill, this is clear from the numerous findings of Attic vase-painting obtained with both techniques of red-figure and applied colour. On the north hill, although the extensive modifications made in the I st century A.D. (erection of the amphitheatre), there is an alignment of walls belonging to structures dated from different periods (Archaic, Classical, Hellenistic ages); it is, thus, likely to suggest a continuation of the urban scheme. In the area of the valley bottom, remains originally belonging to a votive deposit and frequent discovering of fine imported pottery confirm an endurance of life in the city of 5th and 4th centuries B.C. The Roman conquest in 294 B.C. by the Consul Lucius Postumius Megellus, is mentioned by Livius. Archaeology does not support this date and the evidence of the first two centuries after the conquest is scant. A destruction layer for fire, datable from the first decades of the Ist century B.C., suggests that Roselle was involved in the de-structions made by Silla, together with other Etruscan cities (Talamone, Vetulonia, Populonia, Volterra and Fiesole). With the Lex Mlia and the Lex Plautia-Papiria, the inhabitants of Roselle, under Roman domination, were included in the tribe Amensis and they became Roman citizens. The main means of Romanization of the conquered territories was the colonisation, which had two main purposes: to control the conquered territory and to refuse the external attacks. South to Roselle, the colony of Cosa is an example of how the colonisation interested, besides the urban centre, the whole territory, with infrastructures such as bridges, roads, harbours, and with the centuriatio.
On the contrary, the conquest of Roselle did not require the colonisation and part of the territory, sometimes wide sectors, was left inviolate, although the Roman control was not less strong than anywhere else. Only during the Roman Imperial age (about three centuries after the conquest) Roselle was interested by an intense building and monumental activity, a result of Roman guarantee and patronage of powerful native families (the Vicird, Bassi). The title of colonia, although purely honorary, was conferred to the city, as testified by literary sources (Pliny the Elder, Nat.Hist. 111 51) and archaeological evidence, such as the inscription Pub(lica) Col(onia) Rus(ellana) stamped on lead water pipes placed in the city centre. Thus, the monumentality of the city dates to the Imperial age, at the same time than the economic acceleration favoured by the Imperial politics: the amphitheatre, the monumental forum, the basilica of the Bassi as well as the baths date to this period. In the Late Imperial age, Roselle met with the decadence which Roman cities progressively suffered: Rutilius Namatianus, a 5th century A.D. author of a poem on a travel along the Italian coasts, does not mention Roselle, probably because the latter did not longer face the coast. However, in this time an actual building activity was missing: most of the Roman Imperial structures were adapted to other uses, and they consequently changed their aspect and turned their original purpose. In the 5th century A.D. Roselle was a bishop's seat and it had a large diocese: the first known bishop is Vitalianus in 499 A.D. Between the end of the 6th and the beginning of the 7th century the city was conquered by the Longobards. In 787 Carlus Magnus offered the territories of Populonia, Roselle and Sovana to Pope Hadrian, but such a proffer was limited to the only Sovana, since the Holy Roman Empire continued to control Roselle through the loyal episcopacy of Lucca, which owned the city back from the Longobard period. In 862 the bishop of Lucca, belonging to the Aldobrandeschi family, gave several properties, among which was Roselle, in place of others belonging to his brother, which were closer and thus easier to be administered. From this time onwards the history of Roselle is strictly connected with the Aldobrandeschi family's events. However, in the Mediaeval Age Roselle was only a small site and it did not occupy the wider area of the Roman city. In 1138 a bolla of Pope Innocenzo 11 (1130-43) ratified the transfer of the diocese to the nearby site of Grosseto, the existence of which is testified from the beginning of the 9th century. The decree ordered the end of Roselle civitas, which from then was named castrum and progressively abandoned. The territory of Roselle followed the destiny of the whole Maremma: in 1243 Siena, for the loyalty demonstrated to the Ghibellines, obtained from the Emperor Federico II of Sweden (1220-50) the investiture of the Aldobrandeschi property. This fact juridically legitimated the expansionist policy of Siena, which progressively replaced the powerful family in the control of Maremma. Roselle, except for rare presences until the 17th century, was abandoned by the last few inhabitants, and became

< ...a wilderness of rocks and thickets - the haunt of the fox and wild boar, of the serpent and lizard... >

as seen by George Dennis, a 19th century English diplomat and erudite, when he paid a visit to Maremma