The Council of Nicea in 325 CE marked a bad day for the Jews under Roman rule. Constantine, emperor and honorary bishop (though there's some disagreement as to whether he ever actually became a Christian), declared Christianity to be the official religion of Rome. He viewed the Jews as the false Israel which had refused to accept Jesus as the Savior. Laws were made against them.
Despite these troubles and tensions the Jews of Judea under Constantine's rule continued to function fairly normally. The Judean academies of Tiberias, Tzippori, and Lydda continued to attract students. Recent archaeological digs in Israel have uncovered remarkable mosaic floors at Tzippori indicating that the city was quite wealthy during this time period. The interpretations and discussions based on the Mishnah and the Tosefta continued to be developed.
One of the most important accomplishments of Emperor Constantine was to have had a mother named Helena. Helena definitely became a Christian. She was so turned on by the faith that she traveled to Judea to make a pilgrimage to all the sites where the stories of Jesus took place.
Until that time, no one had really concentrated on the sites in Judea where Jesus had presumably walked and worked. Helena not only toured the Christian sites but she also named them.
Although Christians knew approximately the path taken by Jesus on his way to the cross (the Via Dolorosa, the Way of Pain), they didn't know exactly where each specific event (called stations) of that walk took place. Helena showed them, and the precise spots which she indicated became accepted by Christian tradition. It is possible that she not only showed them where the known events took place; she may have introduced some new events as well, thus creating some of the fourteen Stations of the Cross.
Helena showed the stump of the tree which provided the wood for Jesus' cross. She found the wood itself from the cross upon which Jesus died. She indicated the spot where the miracle of fish and bread took place. She pointed to the place where Jesus stood when he gave his Sermon on the Mount. She marked where Mary was told that she would give birth to Jesus (an event called the Annunciation). She indicated which room was Joseph's carpentry shop. She showed the spot where Jesus was born, the field where the shepherds saw the star, inn where the Good Samaritan took care of the beaten man.
She had a magnificent church built on the spot where Jesus was crucified and buried (the first of the Holy Sepulchre churches). She indicated where Mary went into an eternal sleep. She pointed to where Judas kissed Jesus thus identifying him to the Romans. She spotted the room where Jesus turned water into wine at Kafr Kana. She identified the spot where Jesus was baptized by John the Baptist.
To be sure, some of the sites which Helena pointed out were already considered holy shrines commemorating specific events in Jesus' life. Helena's guided tour lent a great deal of legitimacy to the original traditions; no one was arguing with the mother of the emperor of Rome.
Thanks to Constantine's mother, the Christian tradition today has as many holy sites and shrines in Israel as do the Jews and Muslims. Judea became the Holy Land for Christians, and thousands made pilgrimages to the holy sites. Instead of being just a small outlying province of the Empire, Judea became a Christian center.