Since October 12, 2013, Montegrosso has been a twin municipality with Pontevès, a village in Provence in the French department of Var and has 573 inhabitants. Pontevès is part of the Brignoles district. In 1477 the two paths crossed for the first time: Pontevès was depopulated as a result of the plague epidemic. The diocese and the other church leadership dealt with this problem. To get a new population, 30 families from Montegrosso were found willing to settle in Pontevès. In exchange, a piece of land and a herd of land were owned.

According to some historical sources, Montegrosso originated around the beginning of the 11th century. One of the first official reports dates from 1207, when the Counts of Ventimiglia split up with the Scarella family, the lords of Garessio. In 1297 a new set of regulations was established, making the Montegrosso P.L., Cosio di Arroscia, Mendatica and Borghetto d'Arroscia settlements a "lending area" for the lords of Garessio, the Scarella family. The latter sold the lending area in 1321 to the Counts of Lengueglia, who divided it up in 1362 with the Counts of Ventimiglia. In 1445, Count Gasparo, descendant of the Counts of Ventimiglia, transferred feudal justice to the Counts Tascaris from Tenda. In 1625, the village was razed to the ground in the battle between the Duchy of Savoy and the Republic of Genoa. From 1973 to December 31, 2008, Montegrosso P.L. part of the High Valley Arroscia Mountain Municipality (Comunità montana Alta Valle Arroscia). After this she is part of the mountain community of the olive tree and the High Valley Arroscia (Comunità montana dell’Olivo and Alta Valle Arroscia).

The San Biagio parish church with a parish in Baroque style still contains the original door that was placed there late in the 15th century.
If you walk down Via Sant’Anna in a south-west direction and, after the horses, keep left, following the path, you will come to the patron saint of Sant’Anna, the saint who watches over our street.