Original Adventures Reincarnated #1: Into the Borderlands (Hardback) - Rules of Play says:

This tome is an homage to the origins of Adventure that began decades ago with B1: In Search of the Unknown and B2: The Keep on the Borderlands. Herein you will find high-quality scans from multiple printings of the original first edition adventure modules, plus commentary by such gaming luminaries as Luke Gygax and Mike Mearls. Full fifth edition conversions of both adventures are included, as well as brand new additional adventure locations to further expand and develop the Borderlands. This is a fully playable mini-campaign to start off your new fifth edition adventures, with a distinct old-school vibe.