Originally, the entire story of Jesus' death and resurrection was celebrated on a single day, Easter Sunday. Pilgrims, who travelled to the Holy Land from year 300 and on, brought back graphic stories of how the churches staged dramatic events from the Gospels. The Easter Liturgy, as we know it today, gained its present form during Pope Pius XII in 1955.
Source:katolsk.no
Easter Triduum
Giotto di Bondone, Capella degli Scrovegni. Padova