How do you create the earth in Minecraft?

I saw a couple of servers that created the earth in Minecraft without houses etc. But still very nice.

I would like to know how to do that because I have a few ideas for cool features and I would do a server like that too.

As far as I know, such maps are free to download.

Mod Terra 1: 1 I don't know if it works but I've seen something about it