The church housing Bosco's remains was built in 1865-1868 to plans by Antonio Spezia.
According to legend, a vision of the Virgin Mary appeared in a dream to John Bosco in 1844 or 1845 and revealed the site of the martyrdom of the Turinese saints Solutor, Adventor and Octavius. The Basilica dell'Ausiliatrice was built on the site of their death. The church houses the relics of these saints.