Castello Giulio's Brunello di Montalcino is grown in the Villa Santa Restituta zone of southern Montalcino, one of the appellation's warmest and most coveted sectors, where south and south-west facing vineyards sit between 400 and 480 metres on poor, stony soils of silicates and limestone refreshed by altitude breezes. The 100% Sangiovese vines are 20 to 30 years old, and the project is led by Federico Nannetti, who took over from his grandfather Cesare Castelli, maintaining a small-production, family-rooted approach to the estate.

Grapes are harvested by hand in the first decade of October, fermented at controlled temperatures not exceeding 24–26°C, and aged in the traditional manner in large oak vessels — botti grandi — meeting the DOCG minimum of two years in oak within a total ageing period of 36 months, a process that favours transparency and long, graceful tannins over overt wood influence. James Suckling awarded this 2020 vintage 95 points, describing it as precise, juicy and savoury, with bright intensity, refined filigree tannins and refreshing integrated acidity.