CODEX ALEXANDRINUS. This fifth-century C.E. copy of the Septuagint (LXX) is written in Greek uncials (capital letters) and is thought to have originated in Alexandria, as its name implies. It now resides in the British Library in London. The other two prominent copies of the Septuagint, from the fourth century C.E., are the Codex Sinaiticus (found at St. Catherine’s monastery at Mt. Sinai and still there) and the Codex Vaticanus, housed at the Vatican Library. Of the three, Alexandrinus is the most complete.