The best 250 adventure novels of the 20th century

My friend Joshua Glenn is a voracious reader of adventure novels. He's turned me onto tons of great books, and he recently compiled a list of 250 great adventure novels from the 20th century. Many of these books are available on project Gutenberg and other public domain book and audiobook websites. I really appreciate that josh found cover art from early editions of the books, rather than the usually terrible art found on contemporary editions. I want to read them all, starting with Black Magic: a Tale of the Rise and Fall of the Antichrist! (audiobook | e-book)

Marjorie Bowens supernatural fantasy adventure Black Magic (1909). In medieval Flanders, Dirk Renswoude, a lonely craftsman of noble birth, meets Thierry, a young scholar who shares Dirks fascination with the black arts. Against a background of violent storms, mysterious comets, and a Walpole-esque mood of gothic horror, the two experiment with mystic circles, arcane incantations, and the summoning of demonic visions. Although Thierry is afraid of blasphemy, Dirk is ambitious and has sworn allegiance to the Devil in return for worldly power. In fact, Dirk aims to become the Antichrist and Satanic Pope! Nevertheless, Dirk is not entirely villainous he risks everything for Thierry, with whom he has fallen in love and his backstory reveals a surprise twist that makes us sympathetic to his desire for the agency and independence denied to him by his family. Ysabeau, a cold-blooded schemer and murderess character, also becomes a sympathetic and even heroic figure; and Jacobea, the novels tormented heroine, is also well-portrayed.