Archaeological express. El Metro is an economical way to get around - and view Mexico City's artistic treasures

MANY people think of a subway only as a mode of transportation. In Mexico City, ``El Metro'' is a reflection of the nation it serves. While it reminds this developing country that technology can vault it into the future, many of the walls, stations, and signs reinforce ties to Mexico's past. For example, at the Pino Su'arez station, the bustling crowd darts past a monolithic stone temple, which was unearthed when the station was excavated. The serpent was the guardian of the Aztecs' legendary city - until Hern'an Cort'es and his Spanish army demolished the Indian rule in 1521. Now the resurrected temple oversees thousands of commuters who have descended from that great race.

Archaeology, art, and national heroes are reflected in the stations that constitute the nearly 80 miles of underground public transportation. Finely crafted sandstone sculptures of ancient gods are on view at the Insurgentes station, in the center of the city. A helmet-clad warrior appears to be from the Olmec era, an Indian race that is believed to be among the earliest inhabitants of Mexico.

Mayan murals and meticulously cared-for marble floors are featured at the Bellas Artes station, while impressive murals can also be examined at the Coyoacan station on the more peaceful south side of the city.

El Metro is easily the fastest, cleanest, and safest way to see Mexico City. In this metropolis of approximately 18 million inhabitants, the streets above ground can be a motorist's nightmare - especially in rush hour.

Below ground, however, El Metro carries nearly 4 million people each day in its trains of orange cars. The cars' rubber tires, as opposed to steel wheels on many other subway systems, cushion the ride and dramatically cut the noise.

For a tourist with a limited amount of time and money the subway is an excellent form of transportation. The fare for each trip is less than one-half an American cent. If modern-day Mexico interests you, stop at the Balderas station in the downtown area. At this station young entrepreneurs will try to sell you anything, from handcrafted dolls to native foods (which I do not recommend you eat). Animals are sometimes brought here to perform for commuters and to be offered for sale. Retail activity is technically forbidden, but authorities typically look the other way.

In addition to being aesthetically pleasing and full of activity, the subway system is ``user friendly.'' Most tourist hotels are located near the National Auditorium station and the Chapultepec stop. Maps indicate which stops are located near tourist attractions, which are easily identifiable because many stations are named after the popular sites.

Twenty minutes from the downtown area, for example, is Mexico's famous Basilica and shrine to the Virgin of Guadalupe. Conveniently, the subway station is called the ``Basilica.''

Likewise, stations near Chapultepec Park and Bellas Artes are named after those sites.

A knowledge of Spanish is not necessary when riding the subway. Besides having a name, each station uses a symbol. For example, the stop for the National Palace uses the country's official emblem - an eagle with a snake in its grasp.

Every line in the system is also color coded. By recalling the bright colors and the station signs, a foreigner without knowledge of the language can find his way around.

Subway tickets are purchased in a little booth near the station's gate. One ride is only 20 pesos - which is probably one of the best bargains a traveler can find in Mexico City.