Gennaro Della Monica was born in 1836 in Teramo where his father Pasquale had moved to teach drawing in the local Real Collegio, after being expelled from Naples as a suspect of belonging to the Carboneria.
Right from his father he was educated in the art of drawing and in the use of colors. He moved seventeen years old to Naples, in 1852, to study at the Academy of Fine Arts in Naples. In the capital he met Michele Cammarano, Gabriele Smargiassi, the brothers Filippo and Nicola Palizzi, originally from Vasto. He then moved to Milan where he became friends among others, with Gerolamo and Domenico Induno.
From 1863 he was in Florence, where he stayed for a few years and met Vincenzo Cabianca, Giovanni Fattori and Telemaco Signorini. Here he met the countryman Giannina Milli, famous improvisational poet but above all refined intellectual, animator of salons and cultural circles, confidant of artists and councilor of politicians.
His paintings were exhibited and admired in the Tuscan capital. From this period is the work Salvator Rosa among the brigands purchased by the emissaries of the House of Savoy, on behalf of the King Vittorio Emanuele II.
He dedicated himself in particular to historical painting but he also owes him an intense activity as a portraitist and especially as a landscape painter. There are numerous works that propose corners and glimpses of the territory of the Gran Sasso and Monti della Laga. Among his interests, the practice of photography must certainly be remembered.
During the eighties of the nineteenth century, on the ruins of the ancient church of San Venanzio, which had been transformed by the French into a powder magazine, began the construction of its castle in neo-gothic style, now owned by the Municipality of Teramo.
Exponent of the secular world and affiliated to the Masonic lodge "Melchiorre Delfico", Della Monica was active and present in the civil life of the city. He drew the uniforms of the town band at the time of the direction of Maestro Costantini. He was involved in the controversy for the restoration of the Sanctuary of the Madonna delle Grazie and tried to avoid the destruction of the ancient temple, which was later built for the benefit of a Renaissance-style reconstruction.