In the late 4th century CE, a Spanish nun by the name of Egeria made a pilgrimage to Jerusalem and described what she saw to her sister nuns. The pilgrimage industry had grown substantially in the previous 50 years or so since Helena, mother of the Emperor Constantine had arrived in the Holy Land, determined to find the sites where the stories about Jesus had occurred. Once found, Helena worked to erect churches on those sites, and those Christians who had sufficient resources, both in time and money, could experience what it must have been like to walk with Jesus during his earthly ministry.
It is not surprising that during the week before Easter, there were rituals at the various sites associated with the Jesus’ last days on earth. The week began on the Saturday of the weekend before Easter, with the remembrance in Bethany of the day that Jesus rested with his friends. On the Sunday before Easter Sunday, there was a re-enactment of Jesus triumphant procession into Jerusalem, greeted by people bearing palm branches. On Thursday, the congregation gathered in the cave where Jesus met with his friends and kept vigil all night. On Friday, the congregation gathered to kiss the wood of the true cross (which Helena also discovered), and from the sixth to the ninth hours, lessons were read, hymns sung, and the congregation mourned. On Saturday, a paschal (Easter) vigil was held.
While those who were able to make the pilgrimage to Jerusalem for Easter got the benefit of walking through the events of Jesus’ last days, most Christians would never be able to make the trip. So, many of the rituals that were originally celebrated in Jerusalem at the holy sites were taken back to local parish churches. In that way, all Christians were able to make this sacred pilgrimage. These services became basis for Holy Week observances, and are still observed, much the same way, 2000 years later.