The Aztecs Were Highly Skilled Engineers

Tenochtitlan was a little swampy island in Lake Texcoco in the Valley of Mexico when the Aztecs founded it in 1325. This created a significant issue for the Aztecs, as whatever structures they constructed would sag due to the region's geology. They devised a clever solution to this problem by pounding wooden piles into the lakebed below water in close-packed formations to give a solid foundation for their structures. To improve strength, the pilings were encased by volcanic stone. The fact that their structures did not tumble or sink despite being built on top of these foundations is a credit to their incredible engineering abilities. Tenochtitlan to the mainland could only be reached by boat.

The Aztecs built three causeways to connect their city to the mainland, one to the north, one to the south, and one to the west. They accomplished this by driving two lines of wooden stakes down into the lake bottom and filling the area between them with soil and stones until the water level was attained. The causeways were built straight and up to 45 feet wide. Bridges would open to allow boats to travel through and to defend the city in the event of an invasion, interrupting them.