Codex Calixtinus
The Codex Calixtinus (or Codex Compostellus) is a manuscript that is the main witness for the 12th-century Liber Sancti Jacobi ('Book of Saint James'), a pseudepigraph attributed to Pope Calixtus II. The principal author or compiler of the Liber is thus referred to as "Pseudo-Calixtus", but is often identified with the French scholar Aymeric Picaud. Its most likely period of compilation is 1138–1145.