Ancus Marcius is merely a duplicate of Numa, as is shown by his second name, Numa Marcius, the confidant and pontifex of Numa, being no other than Numa Pompilius himself, represented as priest. The identification with Ancus is shown by the legend which makes the latter a bridge-builder (pontifex), the constructor of the first wooden bridge over the Tiber. It is in the exercise of his priestly functions that the resemblance is most clearly shown. Like Numa, Ancus died a natural death.
See Livy i. 32, 33; Dion Halicarnassus iii. 36-45; Cicero, ''De Republica,'' ii. 18.