The Carmentalia. A festival for Carmenta held also on the 15th of January. This festival uniquely skips not one day but three between the first and second day of the festival. Carmenta was a seer and the mother of Evander, who founded the town of Pallantium or a goddess of prophecy.
Juturnalia. Festival for Juturna, the personification of springs and sister of Turnus in Vergil. Temple for Juturna dedicated by Augustus in 2 B.C.
In 29 B.C. Augustus closed the doors to the temple of Janus in the Roman Forum to symbolize peace.
Theodosius I born in A.D. 347. in Spain. See Why was Theodosius called the Great FAQ
"Hints for Teachers," by John F. Gummere. The Classical Journal, Vol. 32, No. 4. (Jan., 1937), pp. 242-248.