The Oldest Book
The Codex Siniaticus, handwritten in Koine Greek during the fourth century CE, is one of the most important books in history, and the oldest book to have survived Antiquity. It contains part of the Septuagint (the Greek translation of the Old Testament), the New Testament, and other religious texts. Not only is it old, it contains not just the texts, but additions, corrections, and commentary. You can view it in its entirety in an online project that reunites all the parts of the book that are held in different libraries around the world.