How would you make a 3D model of the Aztec city Tenochtitlan?

My class has to make a model of a scene from the history of Mexico, and I want to make a model of lake Texcoco with causeways, mountains, and the island city of Tenochtitlan (including the small villages around the lake. I was thinking of using blue Play-doh as water, and star wars monopoly pieces as buildings, but what can I use for the cities, causeways and chimpanas (or whatever the farms were called)? Thanks for the answers!