The lighthouse world is a mysterious world that can be found looking on the left when you enter the stormgate to Cool Ranch. Currently, this mysterious world has been classified as either, Empyrea, Rajah. Or something else.
This is not Marleybone, since Marleybone's world icon is the Royal Museum with the Big Ben, and we go to marleybone at level 50+.
The unnamed world is a lighthouse sitting on top of rocks.