What is located on the site where the aztec capital once existed

Mexico City

Explanation:

Through-out what now we know as Latin America, the invaders ("conquerors") slaughtered, steal from the native tribes and they took them as slaves. After subjugating them they use several methods to keep them down like religion and violent repression, something common was to take their cities and destroy their constructions to symbolize they were in control.

answer; eliminate parking problems in cities, because a car took up only half as much space as a horse and buggy;

it is a better alternative