Fattoria San Giusto a Rentennano is a famous, historical Tuscan wine estate known for both Chianti Classico and high-quality, single-variety IGT wines. Located 15km (9 miles) to the northeast of the Renaissance city of Siena, the winery is owned and run by the Martini di Cigala family in the village of Gaiole. At one time, the estate was in the ownership of the famous Ricasoli family (Baron Bettino Ricasoli wrote the original Chianti blend recipe in 1874 that established Sangiovese as the dominant grape). The estate passed into the ownership of the Martini di Cigala family through marriage in 1914. The winery and cellars are in what was once a medieval convent for Cistercian nuns. In the 13th Century, it was restructured into a fortress whose underground fortifications are now the winery's cellars. The modern estate occupies 160 hectares (395 acres) of land with just over 30 hectares () devoted to vineyards and 11 hectares () to olive groves. The vineyards have an average elevation of 270m (885 feet) with a southeast exposure and they benefit from a high diurnal temperature range. San Giusto a Rentennano's vineyards have been certified organic since 2006. San Giusto a Rentennano makes a Chianti Classico and a Classico Riserva, but the winery's fame comes from its two red Toscana IGT wines: a very limited production Merlot called La Ricolma, and a 100-percent Sangiovese called Percarlo. The winery has exacting standards and is prepared not to produce Percarlo in poor vintages, such as happened in 2000 and 2002. San Giusto a Rentennano also makes a highly regarded vin santo-style sweet passito bianco wine that carries the estate name and uses the Toscana IGT designation.