Some derive the name of Aventine from Aventinus-Silvius, king of Alba, who was buried here;[172] others from Avens, a Sabine river; while others say that the name simply means "the hill of birds," and connect it with the story of the foundation of the city. For when it became necessary to decide whether Romulus or Remus was to rule over the newly-built Rome, Romulus seated himself upon the Palatine to watch the auspices, but Remus upon the rock of the Pseudo-Aventine. Here Remus saw only six vultures, while Romulus saw twelve, but each interpreted the augury in his own favour, and Remus leapt across the boundary of the Palatine, whether in derision or war, and was slain by his brother, or by Celer, one of his followers. He was brought back and buried upon the Aventine, and the stone whence he had watched the vultures was thenceforth called the Sacred Rock. Ancient tradition places the tomb of Remus on the Pseudo-Aventine, but in the middle ages the tomb of Caius Cestus was believed--even by Petrarch--to be the monument of Remus. Some authorities consider that when Remus was watching the vultures on the Pseudo-Aventine, that part of the hill was already occupied by a Pelasgic fortress called Romoria, but at this time and for long afterwards, the higher part of the Aventine was held by the Sabines. Here the Sabine king Numa dedicated an altar to Jupiter Elicius,[173] and the Sabine god Consus had also an altar here. Hither Numa came to visit the forest-gods Faunus and Picus at their sacred fountain: Lucus Aventino suberat niger ilicis umbra, Quo posses viso dicere, numen inest. In medio gramen, muscoque adoperta virenti Manabat saxo vena perennis aquæ. Inde fere soli Faunus Picusque bibebant.[174] By mingling wine and honey with the waters of their spring, Numa snared the gods, and compelled them to tell him how he might learn from Jupiter the knowledge of his will, and to reveal to him a charm against thunder and lightning.[175] The Sabine king Tatius, the rival of Romulus, was buried on the Aventine "in a great grove of laurels," and, at his tomb, then called Armilustrum, it was the custom, every year, in the month of October, to hold a feast for the purification of arms, accompanied by martial dances. A horse was at the same time sacrificed to Janus, the Sabine war-god.[176]