God of door and gate (iānua) (the term also for the type of honorific gateway that we misleadingly call ‘triumphal arch’). Like a door, he looked both ways, and is therefore depicted as a double‐headed and bearded man (the image chosen for many early Roman coins). More generally he controlled beginnings, esp. as the eponym of the month January, and was linked with the symbolism of the gate at the beginning and end of military campaigns. This was most famously expressed in the ritual of the closing of the shrine of Janus Geminus in the Forum in times of complete peace: under King Numa, in 235 bc, three times under Augustus, and more often in the imperial period. Domitian transferred the cult to a new shrine in the forum Transitorium (see forum nervae).
This shrine (as depicted on coins) was little more than a gateway itself. It was probably geminus—‘twin’—in being a four‐way arch, like the ‘arch of Janus’ which survives in the forum Boarium.
Subjects: Classical Studies.