Christmas, why December 25th?

Scholars can't agree on exactly when Christ was born, but how long has Christmas been celebrated on December 25?

The exact circumstances of the beginning of Christmas as we know it remain obscure. The oldest existing record of a feast to celebrate the birth of Christ is in the Roman almanac called the Chronographer of 354 or the Philocalian Calendar. This almanac noted that a festival commemorating Christ's birth was observed by the church in Rome in the year 336. Chronographers of the third century were the ones who reckoned December 25, around the winter solstice, as the most likely day of Christ's birth. Many historians believe that the church stirred up interest in a festival at this time of year to counter the pagan festivals surrounding the solstice, but no historical document proves Rome's involvement. The record shows that such a festival was adopted throughout the Christian world by the year 458. The word Christmas comes from "Christ's Mass."