In Chapter Eight, The Power of Rome in the Sixth Century, of The Beginnings of Rome: Italy From the Bronze Age to the Punic Wars (Circa 1,000 to 264 B.C.), T.J. Cornell discusses the walls and boundaries of Rome, and mentions three related festivals: Terminalia, Robigalia, and Ambarvalia.
Terminalia, named after the god Terminus who protected boundary markers. (Wikipedia, as usual handle with care)
TERMINAʹLIA, a festival in honour of the god Terminus, who presided over boundaries. His statue was merely a stone or post stuck in the ground to distinguish between properties. On the festival the two owners of adjacent property crowned the statue with garlands and raised a rude altar, on which they offered up some corn, honeycombs, and wine, and sacrificed a lamb (Hor. Epod. II.59) or a sucking pig. They concluded with singing the praises of the god (Ovid. Fast. II.639, &c.). The public festival in honour of this god was celebrated at the sixth milestone on the road towards Laurentum (Id. 682), doubtless because this was originally the extent of the Roman territory in that direction.
The festival of the Terminalia was celebrated a. d. VII. Kal. Mart., or the 23d of February on the day before the Regifugium. The Terminalia was celebrated on the last day of the old Roman year, whence some derive its name.