ante diem xv kalendas apriles

Festival of Mars (Day 19)

Quinquatrus (Day 1) -- a festival celebrating Minerva's birthday (maybe)

rites in honour of Minerva (obviously connected to the above)

11 B.C.E. -- Herod dedicates his renovated Temple in Jerusalem

303 A.D. -- Martyrdom of Pancharius of Nicomedia

363 A.D. -- fire destroys the Temple of Apollo on the Palatine