Ancient Aztec floating gardens that fed 200,000 destroyed by Spanish in 1519 called Chinampas

Mexico city was formerly an island that fed 200 000 inhabitants from floating gardens called chinampas. During the Aztec Empire, 200,000 people lived on an island in the middle of a lake Tenochtitlan, now Mexico City. It was the biggest and best-fed city in the world and completely surrounded by water. They survived from floating gardens, that converted the marshy wetlands of Lake Texcoco into arable farmland called chinampas.

Each garden was 300 feet long by 30 feet wide. 

To make a garden, workers weaved sticks together to form a giant raft and then then piled mud from the bottom of the lake on top of the raft to create a layer of soil three feet thick. The rectangular gardens were anchored to the lake by willow trees planted at the corners. Each garden was lined on all sides by canals to allow canoes to pass with workers and materials. 

This network of gardens extended for 22,000 acres across the surface of the lake. The floating gardens were companion planted with corn, beans, squash, tomatoes, peppers, and flowers and these incredible gardens yielded seven crops per year.

In 1519, they were discovered by Cortez and the Spanish, who documented the incredible self sufficient city before ordering the destruction of the chinampas.