That Ligorio was gathering material for his encyclopedia on antiquities in the 1540s, contemporary with the activity of the academy [della Virtù], cannot be coincidental. He certainly was aware of the academy's paln, because at least two of its members in 1541 were his friends or acquaintances. One was his close friend the poet Francesco Maria Molza and the other war the Frenchman Guillaume Philandrier, whom Ligorio describes as a „divine observer of Vitruvius.“ In turn, Philandrier in 1552, in his Annotationes to Vitruvius, acknowledged receiving images of ancient coins depicting circuses from „Our Pirro Ligorio, commendable (non contemnendus) painter and student of antiquity.“

For the most part Tolomei's projected study subjects for the academy parallel many of Ligorio's books on antiquities. Among his Neapolitan manuscripts, Ligorio devoted two books to tombs, statues and effigies, weights and measures, Greek and Latin inscriptions, and Greek and Roman medallions. In his later version of the encyclopedia at Turin he has an extended entry on „grottesche“. It is interesting that while the numerous members of the academy completed little of their program, one man, Ligorio, wrote at least twelve volumes on similar subjects: tehn manuscripts in Naples, one in Paris (Bibl. Nat., MS Ital. 1129), and another in Oxford (Bodl. Library, MS Canonici Ital. 138). 

On the basis of the inscriptions and medallions recorded in his manuscripts, Ligorio has been very bitterly accused of being a forger. [Fn. 56: …] Even during the sixteenth century a few scholars were uneasy about inscriptions reported by Ligorio. So his friend the learned humanist Bishop Agustín, when he wrote the antiquarian Onofrio Panvinio on June 25, 1558, requesting a particula inscription, warns Panvinio that „it should not be that of Pirro who sometimes writes his own interpretation in order to overcome some contention.“