Six of the most mysterious and legendary ancient empires from Golarion's past cast a long shadow into the present in this secret-packed new sourcebook. Explore the monolithic, jungle-draped ziggurats of the ancient cyclops ruins of Ghol-Gan, walk among the towering, megalithic ruins of sin-shrouded Thassilon, or seek your fate among the trap-laden pyramid tombs of ancient Osirion, along with three other legendary realms. Each of the six lost kingdoms detailed in this book come rife with adventure hooks, details on ancient treasures, and statistics for the deadly guardians who lurk there still.