Although most people tend to think of them as a modern phenomena, one of the first recorded examples of a UFO actually came from ancient Rome.
In 218 B.C., a written account reports that a fleet of gleaming ships appeared to be floating in the sky of Rome. That wasn’t the only one, either—in A.D. 150 a report from an area right outside of Rome described “a beast like a piece of pottery about one hundred feet in size, multicolored on top and shooting out fiery rays, landed in a dust cloud.”
The Roman author Julius Obsequens, believed to have lived in the fourth century A.D., drew on Livy as well as other sources of his time to compile his book Prodigorium liber, which describes many peculiar phenomena, some of which could be interpreted as UFO sightings. Here are just a few examples:
216 B.C. Things like ships were seen in the sky over Italy… At Arpi (180 Roman miles, east of Rome, in Apulia) a round shield was seen in the sky. At Capua, the sky was all on fire, and one saw figures like ships…
99 B.C. When C. Murius and L. Valerius were consuls, in Tarquinia, there fell in different places… a thing like a flaming torch, and it came suddenly from the sky. Towards sunset, a round object like a globe, or round or circular shield took its path in the sky, from west to east.
90 B.C. In the territory of Spoletium (65 Roman miles north of Rome, in Umbria) a globe of fire, of golden colour, fell to the earth, gyrating. It then seemed to increase in size, rose from the earth, and ascended into the sky, where it obscured the disc of the sun, with its brilliance. It revolved towards the eastern quadrant of the sky. [Harold T. Wilkins, Flying Saucers on the Attack, pp.164-69]
A later chronicler of inexplicable phenomena, one Conrad Wolffhart (a professor of grammar and dialectics who under the pen name of Lycosthenes wrote the compendium Prodigiorum ac Ostentorum Chronicon, published in 1567), mentions the following events:
393 A.D. Strange lights were seen in the sky in the days of the Emperor Theodosius. On a sudden, a bright globe appeared at midnight. It shone brilliantly near the day star (planet, Venus), about the circle of the Zodiac. This globe shone little less brilliantly than the planet, and little by little, a great number of other glowing orbs drew near the first globe. The spectacle was like a swarm of bees flying around the bee-keeper, and the light of these orbs was as if they were dashing violently against each other. Soon, they blended together into one awful flame, and bodied forth to the eye as a horrible two-edged sword. The strange globe which was first seen now appeared like the pommel to a handle, and all the little orbs, fused with the first, shone as brilliantly as the first globe.