Text, Chi-Rho, brief history of the Chrismon symbol

The symbol chosen by Constantine to express his adherence to Christianity is the Chrismon, formed by superimposing the first two letters of Christ's name in Greek, X (Chi) and P (Rho). The Cross was not used because initially considered an ignominious symbol: crucifixion was a capital punishment reserved for the lowest classes in society and slaves. Additionally, the Chrismon was evocative of solar symbolism, meaningful to both the Christians and to pagan followers of the cult of Sol Invictus, particularly numerous in the army. With Constantine the Chrismon spread throughout the empire, definitively becoming the most important symbol of Christian faith. It is located at the Colosseum, Rome.