The snow-capped peaks of Mexico City's twin volcanos, Popocatepetl and Iztaccihuatl, now extinct are over 17,000 feet high, an interesting side trip from the city. To see Mexico, you really have to feel Mexico, recall the civilization centuries passed. The Spanish built these remarkable aqueducts over 200 years ago, and they are still used today. And then reaching even farther back to the ancient past, here on the Yucatan Peninsula are ruins of the cities of the mysterious Mayan Empire. This one is Chichen Itza. Very little is known about the Mayans, but it is known that they had discovered time periods, such as lunar months and length of the year, and developed a calendar and writing about 1,000 B.C.