Mexico City
Mexico City is one of the largest cities in the world. It is also one of the oldest having originally been the capital of the Aztec empire. That means there is all kinds of history in the city. You can actually see cutting edge modern architecture right next to an Aztec ruin in Mexico City. Of course as a gigantic city there is lots going on. The biggest problem you are likely to face is deciding what to do since you will have so many options to choose from.
One of the main reasons that you would want to visit Mexico City is for the history. The city is actually built on the old capital of the Aztec empire. It has been there for hundreds of years. It is quite a sight to be in the middle of one of the world's largest cities and come across an old Aztec ruin. There are a number of archeological digs going on the city at any one time. Of course there are a number of museums to make it easy to see the history but you can also see it just by touring the city. You will be able to see everything from Aztec ruins to colonial era buildings to the most modern parts of Mexico without ever leaving the city.
Of course one of the biggest cities in the world is going to offer a number of other attractions as well. The night life is very vibrant. Mexicans love to party and this will be very obvious when you visit Mexico City. There are hundreds of night clubs and most of them are hopping all night long. The restaurants are world class serving everything from the finest Mexican cuisine to cutting edge international fare. There is also shopping which is world class, if you can name it you can buy it in Mexico City.
Mexico is also great for the sports lover. You can play or you can watch sports. If you are into playing yourself the most popular choice is golf. The excellent weather and the world class courses are a major attraction. Attending a soccer game in Mexico City is something that everybody should experience. The crowds are huge and very enthusiastic; the play is some of the best in the world as well. And although it isn't for everybody no visit to Mexico City would be complete without seeing a bull fight.
There are also a number of attractions in Mexico City for kids making it a great destination for families. There are a few different amusement parks that you can visit, some of them quite large. The zoo is another major attraction. In addition there are constantly festivals or celebrations of some sort or the other going on. You should have little difficulty finding something to keep the kids entertained during your visit to Mexico City.