Chi Rho in the context of "Bishops of Rome under Constantine I"

An oil lamp is a lamp used to produce light continuously for a period of time using an oil-based fuel source. The use of oil lamps began thousands of years ago and continues to this day, although their use is less common in modern times. They work in the same way as a candle but with fuel that is liquid at room temperature, so that a container for the oil is required. A textile wick drops down into the oil, and is lit at the end, burning the oil as it is drawn up the wick.

Oil lamps are a form of lighting, and were used as an alternative to candles before the use of electric lights. Starting in 1780, the Argand lamp quickly replaced other oil lamps still in their basic ancient form. These in turn were replaced by the kerosene lamp in about 1850. In small towns and rural areas the latter continued in use well into the 20th century, until such areas were finally electrified and light bulbs could be used.

The Via Flaminia (lit. 'Flaminian Way') was an ancient Roman road leading from Rome over the Apennine Mountains to Ariminum (Rimini) on the coast of the Adriatic Sea, and due to the ruggedness of the mountains was the major option the Romans had for travel between Etruria, Latium, Campania, and the Po Valley. The section running through northern Rome is where Constantine the Great, allegedly, had his famous vision of the Chi Rho, leading to his conversion to Christianity and the Christianization of the Roman Empire.

Today the same route, still called by the same name for much of its distance, is paralleled or overlaid by Strada Statale (SS) 3, also called Strada Regionale (SR) 3 in Lazio and Umbria, and Strada Provinciale (SP) 3 in Marche. It leaves Rome, goes up the Val Tevere ("Valley of the Tiber") and into the mountains at Castello delle Formiche, ascends to Gualdo Tadino, continuing over the divide at Scheggia Pass, 575 m (1,886 ft) to Cagli. From there it descends the eastern slope waterways between the Tuscan-Emilian Apennines and the Umbrian Apennines to Fano on the coast and goes north, parallel to Highway A14 to Rimini.

The Battle of the Milvian Bridge took place between the Roman Emperors Constantine I and Maxentius on 28 October AD 312. It takes its name from the Milvian Bridge, an important route over the Tiber. Constantine won the battle and started on the path that led him to end the Tetrarchy and become the sole ruler of the Roman Empire. Maxentius drowned in the Tiber during the battle; his body was later taken from the river and decapitated, and his head was paraded through the streets of Rome on the day following the battle before being sent to Africa.

According to Christian chroniclers Eusebius of Caesarea and Lactantius, the battle marked the beginning of Constantine's conversion to Christianity. Eusebius of Caesarea recounts that Constantine and his soldiers had a vision sent by the Christian God. This was interpreted as a promise of victory if the sign of the Chi Rho, the first two letters of Christ's name in Greek, was painted on the soldiers' shields. The Arch of Constantine, erected in celebration of the victory, certainly attributes Constantine's success to divine intervention; however, the monument does not display any overtly Christian symbolism.

Alpha (Α, α) and omega (Ω, ω) are the first and last letters of the Greek alphabet, and a title of Christ or God in the Book of Revelation. This pair of letters is used as a Christian symbol, and is often combined with the Cross, Chi Rho or other Christian symbols.