A guided tour of Madrid's feats of engineering

Engineers like to illustrate the importance of their work with an example drawn from everyday life: they ask people to think about all the engineering work that makes it possible to turn on a tap- reservoirs, piping, water-treatment plants and so on.

There are 15,000 kilometers of pipes in Madrid alone, equivalent to taking a trip to Havana and back. Now, the lay person has a chance to discover the wonders that lie behind Madrid's great works of civil engineering through the Semana de la Ingeniería de Caminos, a series of guided tours of 20 emblematic sites in the capital, including La Zarzuela racetrack, the irrigation channels in Aranjuez and the El Atazar reservoir.

The initiative, which ends on Sunday, has met with unprecedented success, with more than 2,000 requests to join one of the tours arriving before the start of the event last week. Spanish engineers acting as guides will not only focus on home-grown projects, but also explain their contributions to work in the New York subway system, Kuwait's railway network, and the Panama Canal.

EL PAÍS asked four experts to choose and comment on their favorite works of civil engineering in the capital. The award-winning Javier Manterola, known for his streamlined bridges, unsurprisingly selected two such constructions: Puente de Segovia and Puente de Toledo.

"The Puente de Segovia is by Juan de Herrera, the same person who built El Escorial, which I love so much," says the National Engineering Prize winner. "It is one of the most beautiful period bridges in Spain, and I would even say in the entire world. It is very strict and minimal because back then [in the 1500s] minimalism was already a trend. The Puente de Toledo, by Pedro de Ribera, is a splendid example of Baroque construction, even if it has undergone many ups and downs due to the restoration of the banks of the Manzanares."

Manterola also mentioned La Zarzuela racetrack, designed by two architects in 1941 with help from the engineer Eduardo Torroja. "It is a masterpiece. It has just the right design, with no fancy stuff. It opened up many new worlds because of the way it was structured, and because of the grandstand."

Manterola's other favorite construction is the Santiago Bernabéu soccer stadium, home to Real Madrid. "The structure of the playing field, by Carlos Fernández Casado, is fantastic. At a time when these things were not very frequent, he proposed making stands built with reinforced concrete. It is a role model of a stadium: people are very close to the players, and the latter must surely smell the crowd pressuring them to intimidate the players from the opposing team."

Rosa Arce, an engineering professor, chose El Atazar reservoir, saying that just visiting this work of art is a romantic act in itself. "When you are standing in front of a dam, its volume and its height are impressive. This reservoir causes an interaction between the water, the concrete and the vegetation, creating a beautiful new landscape. And it is tremendously useful, as it provides Madrid with drinking water."

Salvador Sánchez Terán, a former transportation minister, said that his favorites are the overpasses on the A-6 highway. "Before making them, we traveled across Europe, especially Germany. All the bridges we saw were prefabricated affairs with repetitive structures. But Fernández Casado made each of these four overpasses different, and they have enormous beauty- especially the one in the Guadarrama mountains."

The former minister also underscores the importance of the high-speed railway tunnel that bores through these mountains. "This project opens up all of northern Spain- from the Basque Country to Galicia- to high-speed travel, although so far only the Valladolid link has been completed. This work represents a decisive change for communications in Spain."

Miguel Ángel Carillo, dean of the Madrid engineer association, notes that the transportation hubs of Atocha, Príncipe Pío, Moncloa, Plaza de Castilla and Avenida de América provided the much-needed answer to ongoing attempts to improve mobility within the city.

"Thanks to them, we finally managed to bring in commuters from outside the built-up area of the city and connect them with other means of transportation. And although this may seem obvious now, it is far from an easy task," Carillo said.

Semana de la Ingeniería de Caminos. Until March 13 at various locations in Madrid. For more information call 91 308 19 99 or visit www.caminosmadrid.es.