This book [here‘s the site of the US distributor, thanks to John McChesney-Young in the comments] teaches Latin entirely through the medium of the language itself—a common idea for modern languages that should work just as well for ancient ones.
Part I, Familia Romana, covers the essentials of Latin grammar and a basic vocabulary of some 1500 words. The 35 chapters (capitula) form a sequence of events in the life of a Roman family in the 2nd century A.D. Each chapter is divided into 3 or 4 lessons (lectiones) and consists of several text pages followed by a grammar section and three exercises, pensa. At the end of the volume there is a survey of inflexions, a Roman calendar, and a word index, Index vocabulorum.
In Part II, Roma Aeterna, the subject is Roman history as told by the Romans themselves. It opens with a description of the city of Rome on a historical background. This is followed by a prose version of Vergil’s Aeneid I-IV, with crucial passages in the original, and Livy’s Book I supplemented with extracts from Ovid. At first Livy’s prose is gently adapted, but the main part of the book contains unadapted texts by Livy, Gellius, Nepos, Sallust, Cicero, and Horace.