This is the first English translation and the first modern critical edition of Gervase of Tilbury's Otia Imperialia. Gervase wrote the Otia Imperialia in the early thirteenth century for his patron, the Holy Roman Emperor Otto IV. It presents an encyclopedic melange of cosmographical, historical, and geographical information and a wealth of learned and original accounts of folklore and popular belief. It also contains advice to Otto and pertinent remarks on the relationship between Empire and Papacy, together with scientific and theological speculation. The edition also includes Gervase's recently discovered Commentary on the Lord's Prayer. Gervase was a voracious and eclectic reader; his many borrowings are identified in this fully annotated edition.