The Map of Days is one of the many books published in Peculiardom. It has several editions, with the finest one at The Peculiar Archives. Perplexus Anomalous is known for helping of the creation of the first addition.
According to Millard, a team of cartographers, artists, and bookmakers worked on it. It took a lifetime to create it and Perplexus Anomalous drew some of the maps. Millard described it as the finest book in Peculiardom, except the Codex Peculiaris.
Miss Peregrine and her children own a small copy of the book, but it appears to be old and was drenched in water during Hollow City's plot. They lost it during the storm, which caused a major navigation problem.
The copy at the Peculiar Archives was larger than the one Miss Peregrine had. It has colorful pages which are made from calfskin and is edged with cold. Illustrations, legends, and footnotes filled the margins, leaving no empty space nor margin for error.