On the server, there are certain rules employed over claiming land.
Fresh Land, unless bordered with a Lot and signified, is free to build on. Cities may be started on Fresh Land.
Used Land is land which has been built on before, however whatever was built there has been removed. Underground rooms may be found under used land.
Abandoned structures are structures that have simply been left by the owner. They are marked with [ABANDONED] signs in a highly visible place. Players are free to move in to abandoned buildings/cities and renovate them. Abandoned buildings in a city with a City Code that get renovated must be renovated according to the City Code.
Destroyed land is a combination of Used Land and Abandoned buildings.