The Codex Marianus, written in Glagolitic script on parchment, was created at the end of the 10th or the beginning of the 11th century. The manuscript is now kept in the Russian State Library in Moscow (Григ 6, Муз 1689, ф. 87). It is not possible to determine exactly where the manuscript was created (for some it is the Western Serbian regions, presumably Bosnia, others point to the territories near the border with the Republic of North Macedonia), but the latest research points in favour of the Southern Serbian lands, possibly Travunia. It was found on Mount Athos, where it probably arrived in the 14th century, and has been in Russia since 1845. Two folios are kept in the Austrian National Library. The Codex Marianus contains decoration made with pen and ink. It consists of intertwined headpieces and initials. Unusual portraits of the Evangelists, following Byzantine influence from the late 9th and the beginning of the 10th century, deserve special attention.