The correct answer would be Mexico. The Aztec empire was located on an island in what is now present day Mexico City. They had sophisticated gardens which were grown on reed mats. They had a canal system of water travel. The Aztecs had a rather sophisticated calandar system which was based on the sun. The Aztecs had an advanced religious system. It was very barbaric and involved human sacrifice which didn't endear the Aztecs to their neighbors. The Aztecs had a crude form of written language that was glyphs much like the Egyptian writings of heiroglyphs.
Further south, the Mayans had an even more complicated civilization.
We can thank the Aztecs and Mayans for chocolate, corn (maize), potatoes, pumpkins, beans and avacadoes.