I have posted this before, but it's worth posting again.
This film, called The Eternal Gift, was shot on Easter Sunday, 1941. It is solemn High Mass at Our Lady of Sorrows Church in Chicago, and is narrated by Bishop -- then Msgr. -- Fulton J. Sheen.
Our Lady of Sorrows parish was founded by the Servites in 1874. The present church building was begun in 1890 and dedicated in 1902. Our Lady of Sorrows is a national shrine, and was granted the title of basilica by Pope Pius XII in 1956, fifteen years after this film was made. It still looks now very much as it did in 1941 (except for the stupid felt banners).