Self-proclaimed Galileo’s ultimo discepolo, Vincenzio Viviani (1622-1703) strove all his life to become a renowned mathematician. Extolling the supposed purity of Euclid’s geometry, he sought to recover the lost knowledge of the Ancients, and fashioned himself a persona as the last heir of the Euclidean tradition. However, Viviani was not appointed primo matematico before 1666 and spent most of his life working as an engineer for the Tuscan Court, preventing him from devising his geometrical magnum opus as envisioned. Delving into Viviani’s personal archive conserved in Florence with his master’s papers, I will try and paint a different portrait from the one historiography retained.