forum.freeciv.org

As for 3D units there were also these 3D units someone made in Blender several years ago:
http://download.gna.org/freeciv/contrib ... animation/

IIRC the map generator on the server uses a heightmap as a baseline to generate the map. If you could use those values to compute terrain height values, instead of deriving them from the simplified terrain, perhaps it would look smoother?