[1] He was the son of the historical painter Giovanni Battista Castello, and arrived in Spain around 1567 when his father had been called by Álvaro de Bazán, 1st Marquis of Santa Cruz to work on his palace in Viso del Marqués.
As a member of the team of artists led by his half-brother, who also had his other brothers helping, Castello worked in the pictorial decoration of various units of the basilica and Monastery of El Escorial.
It is likely that between 1583 and 1584 that Castello participated in the decoration of the vaults of the vestry and sacristy of the monastery, where some soft modeling figures other than the detail work employed by Granello, may apply to, but documentation mentions only his half brother.
With a repertoire of fantastic and allegorical motifs, and inspired by the designs of Perino del Vaga, the four painters completed in just six months the painting of the nearly two hundred feet across the room, and charged for non-work the inconsiderable figure of 1000 ducados.
Married to Catherine Mata, named his first child in El Escorial in 1586, another painter of his team, Juan Serrano, related to his wife, acted as the godfather.