Casalnuovo originates from Casalvecchio of Etruscan origin of the seventh century. It was found in parts of the necropolis of Casa Nocera and Tolos of Poggiarelle, an exceptional example of funerary architecture of the time, discovered in 1896.
The Roman period has left its vestiges in the Villa della Piave, from which many materials are emerged, including the paws of a lion currently placed in the church of St. Andrew.
In 1551, Casale was subjected to numerous pirate raids. In 1742 Torgioni Tozzetti cites it as the biggest castle of the Marquis areas, naming also the Moreto, existing at that time.
It was considered a center for the good health because of the source and the elevated position compared with the underlying marsh. In 1862 it was called Casale of the Maremma, then Casale and finally from 1900 Casale Marittimo.
In the municipal territory some itineraries of historical and environmental interest develop, each defined with a name and a color in signs that indicate the route. The yellow route 10.5 km 160min goes through the Villa Piave, where Roman excavations were found, until to the factory of the old Magona on the river Cecina.
Green path 3km the archaeological area of Casal Vecchio, which is a ring around the Moreto.
Orange route 3.5 km 140 min moves between olive trees and vineyards up to the maquis area to reach the forest.
In the village you can see the Casale Castle, the clock tower, the Casa del Camarlingo that was part of the old town walls
The town still keeps the town walls, in the center of which there is a characteristic square. On one side there is the church of St. Sebastian built in part with materials, also visible in the facade, of stones of Etruscan tombs and parts of Roman ruins. The St Andrea parish church is of 1305 and in front of municipal building there is vicarage palace. All streets lead to particular views that preserve intact the atmosphere.