looding; perhaps worst of all were the floods that occurred in November 1961 when the river Tamarguillo overflowed as a result of a prodigious downpour of rain, and Seville was consequently declared a disaster zone.
Trade unionism in Seville began during the 1960s with the underground organisational activities of the Workers' Commissions or Comisiones Obreras (CCOO), in factories such as Hytasa, the Astilleros shipyards, Hispano Aviación, etc. Several of the movement's leaders were imprisoned in November 1973. On 3 April 1979 Spain held its first democratic municipal elections after the end of Franco's dictatorship; councillors representing four different political parties were elected in Seville. On 5 November 1982, Pope John Paul II arrived in Seville to officiate at a Mass before more than half a million people at the fairgrounds. He visited the city again 13 June 1993, for the International Eucharistic Congress.
In 1992, coinciding with the fifth centenary of the Discovery of the Americas, the Universal Exposition was held for six months in Seville, on the occasion of which the local communications network infrastructure was greatly improved: the SE-30 beltway around the city was completed, new highways were constructed, the new Santa Justa train station had opened in 1991 and the Spanish High Speed Rail system, the Alta Velocidad Española (AVE), began to operate between Madrid-Seville. The Seville airport, the Aeropuerto de Sevilla, was expanded with a new terminal building designed by the architect Rafael Moneo, and various other improvements were made. The monumental Puente del Alamillo (Alamillo Bridge) over the Guadalquivir, designed by the architect Santiago Calatrava, was built to allow access to the island of La Cartuja, site of the massive exposition.
Some of the installations remaining at the site after the exposition were converted into the Scientific and Technological Park Cartuja 93
