Castiglione della Pescaia, regionally simply abbreviated as Castiglione, is an ancient seaside town in the province of Grosseto, in Tuscany, central Italy. The modern city grew around a medieval 12th century fortress and a large fishery, from which it acquired its designation. Today Castiglione is a very popular tourist destination with attractions that include beaches, natural parks, biking trails, historical Etruscan archaeological sites, a panoramic mediaeval hamlet as well as the natural reserve Diaccia Botrona, a swampy humid environment of historical relevance whose endangered wildlife comprise pink flamingoes, mallards and ducks.

The province of Grosseto is a province in the Tuscany region of Italy. Its capital is the city of Grosseto. As of 2013 the province had a total population of 225,098 people.