Overview
Senius and Aschius are the two legendary founders of Siena, Italy. They were brothers, sons of Remus, and thus Romulus was their uncle.
Traditions developed in Siena, which can not be documented prior to the 16th century hold that after Romulus murdered their father during the Foundation of Rome, Senius (who gave his name to the city) and his brother Aschius were forced to flee Rome on horseback, riding respectively on a black horse and a white one, giving rise to the colors on the Balzana, the coat of arms of Siena.
Some tellings of the legend hold that the brothers were protected by the Gods with a white cloud during the day and a dark cloud at night. They also claim the brothers stole the statue of the Capitoline Wolf from the Temple of Apollo in Rome. However, since the brothers were descendants of Remus, Siena did have a claim to be descendants of one of the siblings nurtured by the she-wolf (lupa), which serves as a symbol of Rome.
The Porta Camollia, in the Walls of Siena, is putatively named after an emissary or soldier sent to lure the brothers back to Rome, but who elected to stay instead.
From Wikipedia (CC BY-SA 4.0).