The reputation he acquired by his Lectiones Apollonianae (1816) led soon afterwards to his being appointed professor at the gymnasium of Posen. On resigning that office in 1819, on account of weakness of the eyes, he went in 1822 to Rome, where he remained for fifteen years. He contributed to Platner's Beschreibung der Stadt Rom, then under the direction of Bunsen, and was one of the principal originators and during his residence in Italy director of the Istituto di corrispondenza archeologica, founded at Rome in 1828. Returning to Germany in 1837 he was appointed archaeologist at the Royal Museum of Berlin, and in 1844 was chosen a member of the Academy of Sciences, and a professor in the university.
Besides a large number of archaeological papers in periodicals, in the Annali of the Institute of Rome, and in the Transactions of the Berlin Academy, and several illustrated catalogues of Greek, Roman and other antiquities in the Berlin, Naples and Vatican Museuma Gerhard was the author of the following works: