From the olive groves and rolling vineyards that surround its stone walls to the Rubelli silks and Carrara marble that fill its rooms, Hotel Castello di Casole is perhaps Tuscany’s most authentic escape. So overwhelming is its Italian-ness that if you close your eyes and listen closely, you can almost hear the sounds of La bohème drifting through the 10th-century castle’s beautifully worn archways. For just a few nights in July, however, those magical melodies will become an inextricable part of the Casole exp…