Answer:
I got banned !!
Step-by-step explanation:
First of all, the biggest challenge of all was precisely living in a marsh which had no solid ground to use as foundation, however,they came up with a clever solution, They embedded thousands of pillings made of wood into the mud along with obsidians (volcanic rocks) in order to provide strength for the foundations; by doing so, they were able to build Tenochtitlán on top of these bases.
The other engineering challenge for the aztecs was the acueduct which ran nearly 3 miles from the heart of the city to the center of the island.