The city of Alcalá de Henares, formerly Complutum, is today a leafy tree, head of a diocese that bears its name. The origin of this tree, its roots, are the holy children Justo and Pastor, aged seven and nine, whose martyrdom took place at the beginning of the 4th century in the Hispano-Roman city of Complutum. By order of the prefect Dacian they were beheaded after declaring their faith and their firm decision not to renounce it. This is how St. Isidore of Seville narrates it:

"When the praetor Dacian arrived in Complutum he ordered everyone to renounce their faith in Christ and offer sacrifices to the idols, otherwise they would be condemned to death after being tormented. In the children, Justo and Pastor, the desire to be martyrs and give their lives for the Lord was ignited. And after throwing to the ground the tablets on which they learned or wrote their first letters, in order to learn better from Christ the Teacher, from school, without anyone calling them, they appear before the judge and publicly proclaim themselves Christians; and well above what is proper for their age, they offer to endure the most cruel torments for their faith in Christ”.