This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Every named month an entry records, January through December, is a Roman month, and Ovid's Fasti is the primary surviving source for how Roman religious tradition itself explained those names and the festivals attached to each one, composed as a poetic calendar that works through the Roman year month by month, naming the god, the festival and the story Roman religious practice itself associated with each date.
Ovid's own account is not a neutral historical record: the Fasti is a literary and religious work of the early first century, written under Augustus, and it sometimes recounts a competing explanation for a name or a festival's origin without settling which one is correct, Janus's own claimed authority over every doorway and threshold among them, so an entry treats the poem as the documented Roman tradition's own account of its calendar rather than as an independently verified history of how the months actually came to be named.
An entry draws on the Fasti for this documented Roman religious understanding of its own calendar, keeping it distinct from the later, unrelated observances that other traditions have since attached to the same twelve civil months without inheriting any of Rome's own reasoning for them.