It has 340 vellum leaves, 13 by 9.8 inches, both sides of which are used, totaling 680 pages which were bound into four separate volumes in 1953. Ten of the pages are illustrations, like the "Chi ro" page seen here. Chi ro are the first letters of Christ's name. It stands out because of the ornate illustrations, combining traditional Christian iconography with the complex and intertwined images of animals and humans found in the art of the British Isles. Even the text pages are filled with elaborate decoration. The text, written with iron gall ink, gives evidence of handwriting by at least three different scribes.
For a long time the book was thought to be created in the time of St. Columba, possibly even by him, but the style of the lettering system suggests it was long after. Proponents of the Columba theory suggest that maybe it was created to mark the 200th anniversary of his death. Various theories place its origin at Iona, or Kells, or started at the former and finished at the latter.
Perhaps one of the most interesting parts of its history is that it survived Viking invasions and other events. The Annals of Ulster record (the first reference to the book) that in 1007 "the great Gospel of Columkille, the chief relic of the Western World, was wickedly stolen during the night from the western sacristy of the great stone church at Cenannas on account of its wrought shrine" (a wrought shrine is the elaborately and richly decorated box for holding a book). The Annals' reference to Columcille (St. Columba's real name) is why scholars link it to him.
The Book of Kells now resides in the Trinity College Library in Dublin. If you'd like your own copy, you can find a facsimile edition here.
For a more lighthearted look at medieval books, how about if tomorrow we look at the first medieval book of jokes?