Thank you ! I read in Auhustus Hare, Walks in Rome. London 1897:

“Up to the time of the Tarquins, the hill bore the name of Mens Saturnius, from the mythical king Saturn, who is reported to have come to Italy in the reign of Janus, and to have made a settlement here. His name was derived from sowing, and he was looked upon as the introducer of civilisation and social order, both of which are inseparably connected with agriculture. His reign here was thus considered to be the golden age of Italy…
Mons Tarpeia, which its southern side has always retained. Niebuhr states that it is a popular superstition that the beautiful Tarpeia still sits, sparkling wath gold and jewels, enchanted and motionless, in a cave in the centre of the hill…

Under Tarquinius Superbus, B.C. 535, the magnificent Temple of Jupiter Capitolinus, which had been vowed by his father, was built with money taken from the Volscians in war. In digging its foundations, the head of a man was found, still bloody, an omen which was interpreted by an Etruscan augur to portend that Rome would become the head of Italy. In consequence of this, the name of the hill was once more changed, and has ever since been Mons Capitolinus, or Capitolium.
The site of this temple has always been one of the vexed questions of history. At the time it was built, as now, the hill consisted of two peaks, with a level space between them. Niebuhr and Gregorovius place the temple on the south-eastern height, but Canina and other authorities incline to the north-eastern eminence…”