Today I’m worrying over the Turris Mamilia, or the Tower of the Mamilii. Really there are only three pieces of evidence.
1) Passages in Festus. The reference is under the entry for the October Horse:
“October Horse” is the name of the horse which is annually sacrificed to Mars on the Campus Martius in the month of October. It is the right- hand horse of the winning pair in a chariot race. There used to be an intense struggle for its head between the inhabitants of the Subura and those of the Sacra Via: the latter hoping to affix it to the wall of the Regia, the former to the Mamilian Tower. And the tail of the same animal is conveyed to the Regia, with speed enough for the blood to drip from it to the hearth, for partaking in a divine service.
(Here’s a French translation.)
3) An inscription, CIL 6.33837 = ILS 7242: “M. Octavius M. l. Attalus centurar[ius] a t. M.” where the t.M. is taken to be a reference to the Turris Mamilia as a topographical marker.
This is not a lot of evidence. Frankly its not absolutely clear that all three pieces of evidence refer to the same ‘tower’. What we make of it all pretty much depends on how one wants to think about the Festus passage. Is this tower an ancient and embedded part of the religious ritual? Is this proof of the Mamilii being part of the archaic Roman landscape on par with the ancient kings? Is some ancient power struggle between two claimants to the throne crystalized in this annual rite? Or was the tower just any old third-century landmark in an otherwise squalled, hot and dirty neighborhood? A point of focus in the district that was co-opted into the ritual contest for convenience sometime after its building presumably well after the origins of the religious festival itself?