Anyone Catholic or otherwise interested in the history of the Church, I highly recommend reading “A History of the Popes” (originally published as “Keepers of the Keys” in 1982) by Sir Nicolas Cheetham, an English classics scholar and diplomat, educated at Christ Church – Oxford.
Sir Cheetham (1910-2002) had a successful career as a British diplomat - first to NATO, then as British Ambassador to Hungary (1961-1963) and Mexico (1968-1972). He was the grandson of a British Parliament Member (House of Commons), and the son of a British diplomat and ambassador's daughter (Russian Empire's last ambassador to Italy). He is also the author of a number of books about history (Mexico, New Spain, Greece).
Sir Cheetham’s “History of the Popes” is a slow read as straight history, but an excellent resource book to learn the history of the Roman Catholic Church.