Founded on the ruins of the glittering Aztec capital， Tenochtitan， Mexico City today is a study in startling contrasts. The "City of Palaces" is home to staggering （令人吃惊的）wealth and unspeakable poverty. The picturesque volcanos and mountains that ring the city makes the city's air pollution the worst in the world. A population center since ancient times， modern Mexico City is one of the most crowded cities in the world， with upwards of 20 million inhabitants.

　　Despite its problems， the city is a vibrant metropolitan area， alive with history， studded（点缀）with parks， and bustling（熙攘的）with the dynamic of the 20th century. There's no end to activities in this great metropolis， whether your tastes run more toward historic attractions， cultural pursuits， shopping or after-hours partying.

　　A 600-plus square block historic district raises blisters（起水泡）on the feet of walking-tourers， but several bus companies provide narrated drive-bys that are gentler on the feet. North of the city are the breathtaking Teotihuacan pyramids of the sun and moon， believed to date from a civilization that flourished between 200 and 400 B.C.

　　For culture lovers， the city boasts more than 80 museums， many devoted to art， to history， and to archeological treasures. The grand avenue， Passeo de Reforma， leads to Bosque de Chapultepec， one of the world's greatest archeology museums.

　　Shopping is everywhere， from large stores and elegant boutiques to street vendors and bustling weekend markets with bright red awnings（凉篷，雨篷）over the stalls. Crafts from all over the country are available and range from bark paintings and beadwork to ceramics and silver. Bargaining at the markets is expected， so be ready to haggle（讨价还价）。

　　Hundreds of bars， discos and night clubs attract the after-hours crowd with live music， margaritas and cold bottles of Dos Equis. As in all big cities， a day in Mexico City can be a 24-hour adventure.