Boboli Gardens
You might not think it, but the Renaissance really gave to us our modern notions of a garden, especially of a formal garden. There is rather a large literature on the subject, if you care to pursue this trail, but you'll have to follow it mainly in the library. Lots of good picture books there and detailed essays. Not much on the Web except for pretty pictures.
You might enjoy finding out more about the Boboli Gardens, though.
They are in Florence, Italy and are accounted among the world's most beautiful.
I include a few pictures here as a sampler.
History of Western Civilization
Boise State University
Last revised October, 2001