He created series of paintings exploring historical themes: anarchy, the wreck of the Titanic, alchemy, Mozart, the French Revolution and its victims, Yekaterinburg and the murder of Nicholas II and his family.
His father was an amateur painter, and as a child, Costantini was crafty, and kept a diary accompanied with newspaper cut-outs, collages, photos and drawings.
He served for a short time in the Italian Navy, and from 1951 to 1954 worked in the Merchant Marine, which enabled him to travel to new cities around the world.
A collector of old illustrated magazines, he used this material to create in his Rapallo home and studio paintings and portraits, which typically include period pieces and advertisements.
[3] Costantini worked primarily in tempera, and his characteristic style appeared "like a sun-illuminated stained glass window in a cathedral .... Events are captured without perspective and on a single plane in a startlingly innovative manner," with highly researched detail and architectural precision that "provide an element of photographic realism that contrasts starkly with the decorative backdrop."
[3] A series of paintings, known as "the anarchists cycle," completed between 1963 and 1979, depicted historic anarchist figures and events, such as Ravachol, Nestor Mahkno, Errico Malatesta, and Mikhail Bakunin, the executions of Francisco Ferrer (by firing squad) and Auguste Vaillant (by guillotine), the Industrial Workers of the World, the illegalist Bonnot gang and the Night Workers, and the assassination of Archduke Ferdinand.
[2][5] He also included an element of subversive anachronism through such details as depicting the policemen firing on strikers in Chicago in 1886, that became known as the Haymarket affair, with the faces of four US presidents and the capture of Ravachol with Toulouse-Lautrec as the arresting officer.