Two books I think should be added are:
Saints and Sinners - Eamon Duffy: This is one of the best near-exhaustive histories of the Papacy.
The Lord - Fr. Romano Guardini: It is, by far, one of the best spiritual and theological reflections on Christ I have found. Fr. Guardini was one of Pope Benedict XVI’s mentors and was the pioneer of the theological style which Pope Benedict used with such efficiency in his own works. Flanery O’Connor, who is on the original list, held Fr. Guardini in the highest regard and has been recorded as recommending The Lord to many of her friends for spiritual reading.
