While veneration of the Blessed Virgin in Zaragoza can be traced to at least the 12th century,[2] the introduction of 12 October as the local feast day in remembrance of the Marian apparition was introduced by the city council in 1640,[3] and approved by the Holy See in 1723.

[4] The national holiday of Spain, first introduced in 1918 and confirmed for the contemporary Spanish state in 1982, also falls on 12 October, chosen for the date of the discovery of the Americas (in the USA known as Columbus Day).

Throughout the day of 12 October, thousands of people dressed in traditional costume, leave flowers at the statue of the Virgin, which has a place of honour in the middle of the Plaza del Pilar.

This cross of flowers is an offering made by the local General Royo Villanova Hospital, a tradition they started in 1960, on behalf of incurable patients with tuberculosis who were unable to attend.

The Glass Rosary parade always starts at sunset each October 13 proceeding from the Iglesia del Sagrado Corazón de Jesús (Church of the Sacred Heart of Jesus), and follows a route around the main streets ending at the city centre.

Rather than using a designated town crier, every year well-known or well-respected personalities of Aragon are selected and awarded the honour of proclaiming the opening of the festival.

The gigantes, or Giants, are a more formal part of the show, with a cast of regal and noble medieval and historic characters that entertain the people with their elegant dances in pairs.

A series of pavilions dedicated to different types of products, such as food, furniture, cars and science are on display for public viewing, and various shows and events are organized to entertain visitors.

During the festival many stages and venues are set up all over the city, for concerts spanning all musical genres, with performances by local and world-famous singers and groups.

The festival ends with grand finale of an outdoor concert in Paseo de la Independencia and a firework show at the banks of the river Ebro.