I created a large bridge up into space. Eventually, you can go so high that you can not make any more land. When you get close to the upper limit and you jump, you become stuck. The only way I can see to escap is to commit suicide. Also, the game will just randomly crash after a while.
I attach my save game to this. If you open it, you'll see my bridge halfway complete. I spent an hour on it so all that construction is gone. However, you'll see how to build all the way up.