This fresco from the so-called sepolcro di Atilio Calatino near the Esquiline Gate, better known as the Esquiline Tomb, dates to the 3rd century BC. For years it was thought to depict a Telamon, as seen in a number of Etruscan tombs, and which were depicted in terracotta on the gates of many Republican towns. Other frescoes from the tomb are better known, showing a battle between the Romans and their enemies, lictors, a triumph.
Because of the depiction of the triumph celebrated by a man of pretorian rank, which are recorded in the Fasti Triumphales, the tomb was linked to A. Atilius A.f. Cn Calatinus, consul of 258 BC, who celebrated a triumph over Carthage in 257 as praetor. Another suggestion was Q. Valerius Q.f. P.n. Falto, who also celebrated a triumph over the Sicilians in 241 BC as propraetor - although that was a naval victory, and the frescoes show land battles. Most others prefer to see it as the 291 BC proconsular triumph of Q. Fabius Maximus Rullianus over the Samnites because of a label on one scene that reads "M. fanius", "St. f." and another "Q. Fabio" - the labels have faded but can be seen in copies made soon after the discovery of the tomb (JSTOR).
Another theory was that because of the 'Telamon' figure shown above, the triumph celebrated was the victory over the Gauls at the Battle of Talamone in 225 BC, making it the 224 triumph of L. Aemilius Q.f. Cn.n. Papus. ... but this is playing with words we know too little about. In fact Telamon figures decorated theatres, tombs and town gates in Italy that had nothing to do with the Battle of Talamone.
Although the wooden cross has become ubiquitous in Christian depictions of crucifixion, before the empire trees and beams were used. Cicero (In Pisonem, 42) mentions being "nailed to a cross".
Livy (Periochae 17, 6) tells in the entry for 257 BC that the Carthaginians crucified their own general, Hannibal Gisco, after their defeat:
Hannibal, dux Poenorum, victa classe cui praefuerat, a militibus suis in crucem sublatus est
We know that Atilius Calatinus also built a temple of Fides on the Capitoline to celebrate his victory over the Carthaginians, and it was decorated with frescoes showing his relative Marcus Atilius Regulus (Val Max IV.4.5-6), who had been tortured by the Carthaginians and died in 255 BC. Some sources give another manner of death, but Seneca (Epistles 98.12) mentions Regulus having overcome crucifixion. Cicero must have meant crucifixion as the 'machine' he describes (In Pisonem, 43): "Marcus Regulus whom the Carthaginians, having cut off his eyelids and bound him in a machine, killed by keeping him awake"
There are a number of different descriptions of the torture and death of Regulus but several include details of his crucifixion, such as Silius Italicus (Punica II, 340-4) which describes him as having been suspended from a cross. Florus (Epitome I.18.25) also mentions suffering on a cross.
So if the 'Telamon' is instead a crucified man, this supports the other iconography as meaning that it was the tomb of Atilius A.f. Cn Calatinus.
here (the source of the two images above, and many more).
The frescoes are now in the Centrale Montemartini (see here).