His funerary altar, which marked the place where he was cremated and was erected as a special honour, features an inscription that provides details about the equestrian statue (Année Epigraphique 1976 no. 144). Marcus Ofillius Celer, who was then duumvir for the second time, ordered that the good deeds of M. Nonius Balbus should be honoured by placing an equestrian statue of the man in the busiest place of Herculaneum, paid for at public expense. Interestingly, this inscription also includes the full text that was to be inscribed in the base of the statue, which specified that the council of the people of Herculaneum had set it up.
In antiquity, it was expected that wealthy people contributed to the community of their own volition. Marcus Nonius Balbus was probably not exceptional in this regard. What is exceptional, though, is that Balbus is the only person from antiquity for which we have this “unusual amount of documentation, with evidence of benefactions, honours during a man’s lifetime, and his burial, in one and the same place”, as per Werner Eck in Beryl Rawon & Paul Weaver (eds), The Roman Family in Italy: Status, Sentiment, Space (1999), page 94.