I started this a few days ago, and bascially what it is is that this is a base for an adventure map, landscape and all. This map was made using WorldPainter and combines base brushes with customized tree brushes from the Realistic Trees Repository.

It has rolling hills, an open plain, a clearing for a city, and karge mountain that is hollowed out if you dig deep enough you will find large cave systems. I will update this tommorow with more pictures and info, but this is it for now.