The Colonnade of St. Peter's, Rome, during the Conclave

Hubert Robert studied and worked in Italy from 1754–65. Upon returning to Paris, he entered the Royal Academy as an architectural painter and full member in 1766. His time in Italy would prove to be influential and classical architectural subjects would dominate his subsequent oeuvre. Interior of the Colonnade of St. Peter's is based on a drawing dated 1758, the same year that Pope Clement XIII Rezzonico was elected. Given his interest in classical subjects, Robert has antiquated his subject by aging the condition of the columns and including a soldier dressed in ancient Roman armor. Similarly, Robert imaginatively portrays the Grotto of Posillipo. Measuring over 2000 feet in length, this tunnel was carved from the volcanic rock by ancient Romans to connect Naples with Pozzuoli. While this passageway was improved by repaving and reinforcing the arches during the reign of Charles III of Naples (1734–59), this structure was never the grand tunnel Robert depicts with coffered vaults and engaged columns.