The 6th century writer John the Lydian wrote a book De Mensibus, On the months, in which he gathered a great deal of antiquarian lore about the Roman world. Book 4 of this work goes through the months, noting the festivals together with other information.
Some time back I commissioned a translation of “March” from book 4. Andrew Eastbourne undertook the work, and has done his usual splendid job.
Both I place in the public domain; do whatever you like with them, personal, educational or commercial.