The Welikia Project traces the historical ecology of New York. It is an incredible, and ambitious project that is exquisitely executed. The result of which is a google map of Manhattan 400 years ago (Mannahatta as it was known through the indigenous Lenape people). You can even enter in specific locations to learn what natural ecosystem likely existed 400 years before. Warning: this can be oddly addictive, and there is an enormous amount of content available.