The Capitoline Wolf’s Romulus and Remus twins were added in the 15th century.
The bronze she-wolf is Rome’s famous emblem of its foundation myth: the abandoned twins were supposedly rescued and suckled by a wolf before being raised by the shepherd Faustulus. The wolf and the children are not necessarily from the same period.
The twins are generally attributed to a late-15th-century Renaissance addition, probably made around 1471 or shortly afterward, when Pope Sixtus IV transferred the sculpture to the Palazzo dei Conservatori on the Capitoline Hill. Antonio del Pollaiuolo is often suggested as their sculptor.
A common mix-up concerns the wolf itself. It was long considered an Etruscan work of the 5th century BC, but modern dating has suggested a possible medieval origin, and scholars remain divided. That debate does not change the conventional answer for the date of the twins: the 15th century AD.