The story of the birth of baby Jesus will be sung and acted out in schools and churches across the Catholic world this Christmas.
But how historically accurate are the well-known Christmas carols and Nativity scenes? Did the manger and the three wise men really exist?
And could Jupiter and Saturn have been the mysterious Star of Bethlehem more than 2,000 years ago?
Here, we take a look back at the first Christmas - and some of the theories that have emerged since...
THE MANGER
WE'VE all sung Away In A Manger... but does the animal feeding trough where Jesus Christ "laid down his sweet head" still exist?
Both early church father Origen in the 3rd Century and St Jeronimo in the 4th Century claimed they had seen the manger in Bethlehem's Grotto of the Nativity, the place where Jesus was supposed to have been born.
The remains of what some Catholics believe was the manger of baby Jesus were brought to Rome from Palestine in 642 after Pope Theodore I was elected pontiff. The relic has been preserved for centuries in Rome's St Mary Major basilica, encased in a silver and glass cradle-shaped container in a chapel under the main altar.
Made from the wood of a sycamore tree, the relics consist of five planks, two of which are nearly a yard long and upright in the form of an X.
Studies have suggested they were supports for the manger, which may have been made out of clay or limestone.
Every year on Christmas Eve they are carried around the basilica and displayed
in front of the altar on Christmas Day.
THE STABLE
WITH no room at the inn, Mary and Joseph took refuge in the stable - hence the typical Nativity scene showing the baby Jesus surrounded by farm animals.
In fact, there is no reference in the Bible to a stable, and no mention of an ox or donkey - they are just assumed because the Bible says he was born in a manger.
But St Justin, who died a martyr in 165, claimed Jesus was
born in a cave. He wrote: "Having failed to find any lodging in the town, Joseph sought shelter in a neighbouring cavern of Bethlehem."
The Bethlehem grotto which is widely believed to be where Jesus was born has been a place of worship for Christians since the 4th Century. The current basilica was built in 565 by Emperor Justinian I.
The exact spot where Jesus is said to have been born is marked, in an underground cave beneath the basilica, by a 14-pointed silver star set into the marble floor.
THE SWADDLING CLOTHES
Over the centuries a number of churches have claimed to possess a relic of the swaddle in which Jesus was wrapped.
One of the earliest was the Sainte-Chapelle in Paris, which listed them in its inventory from 1241, along with what was claimed to be a sample of milk from the Virgin Mary.
The 12th Century Dubrovnik Cathedral in Croatia also claims to possess Christ's swaddling clothes and the cathedral in Aachen, Germany, is reported to possess some of Joseph's clothes.
According to tradition, Mary was without swaddling clothes for her son so Joseph offered to take off some of his.
From the 14th Century, the relic, made up of a brown woollen cloth, was shown to pilgrims at the cathedral every seven years.
THE STAR OF BETHLEHEM
ACCORDING to the Nativity story, the star revealed the birth of the Messiah to the three wise men and later led them to Bethlehem, stopping in the sky above.

In 1614 German Johannes Kepler discovered that a series of three conjunctions of Jupiter and Saturn occurred in 7BC - around the time historians believe Jesus was born. This, he argued, could create a nova, which he linked to the Star of Bethlehem.
Other experts suggest it was a comet. Halley's Comet was visible in 12BC and a comet was seen by Chinese and Korean stargazers in about 5BC.
JESUS'S CIRCUMCISION
THE Bible tells us that Mary and Joseph presented Jesus at the temple eight days after his birth, where he was circumcised and named.
The Church of St James in Rome has on display what it claims to be the altar on which Jesus was placed when he was presented in the temple.
And, bizarrely, a number of churches in Europe have claimed to possess the foreskin of the circumcised baby Jesus.
The earliest recorded sighting came on December 25, 800AD, when Charlemagne, King of the Franks, gave it to Pope Leo II as he crowned him Emperor.
During the Middle Ages, there were as many as 18 other holy foreskins in various towns, including Antwerp, Auvergne and Stoke-on-Trent.
Much more recently in the Italian village of Calcata, a jewel-encrusted case holding what was believed to be the holy foreskin was paraded through the streets right up until
1983. But then thieves stole what is believed to be the last remaining example.
THE WISE MEN
"WE Three Kings of Orient Are" goes the popular carol - but the Bible never says these men were kings, or indeed that there were three. In fact, only the gospel of Matthew mentions the Magi, or wise men, at all.
It has always been assumed there were three because of the number of gifts they bore: gold, frankincense and myrrh. But an early painting found in Rome depicts four men, while others believe there may have been as many as 12.
A group of men called the Magi existed in Jesus's time. They belonged to a priestly sect from Persia, now Iran, described by the Greek historian Herodotus nearly 500 years earlier.
The Magi specialized in astronomy, mathematics and the interpretation of prophecy - hence their calculation the time had come for Jesus's birth. Different names have been given to the Magi - Hormizdah, Yazdegerd and Perozdh in one Persian account.
By the 6th Century they were named as Bithisarea, Melichior and Gathaspa.
The Western church then settled on Balthasar, Melchior and Caspar or Gaspar.
Their fate is even more uncertain. A medieval saints' calendar states they met again at Sewa - Sebaste in Armenia - in 54AD to mark the feast of Christmas. Days later all three died.
Emperor Zeno took what are believed to be their bones from Persia to Constantinople in 490. Then Emperor Frederick Barbarossa of Germany who plundered Italy, brought the relics to Cologne in 1162, where they remain to this day in the cathedral.
THE GIFTS
WHAT happened to the gifts is never mentioned in ¬scripture, but several traditions have developed.
In one, the gold was stolen by the two thieves who were ¬crucified with Jesus, while another has it being entrusted to Judas - before it was misappropriated.
The monks of Mount Athos say the gifts are to be found in a 15th Century golden case in the Monastery of St Paul. ¬Apparently they were part of the relics of the Holy Palace of Constantinople and were displayed from the 4th Century.