I found this real lighthouse-fotos in the internet while searching "living in a lighthouse". If you scroll down in this link, you can see more pics of the interior with designer-furniture. I love it.
this is a great idea for people like me who have not enough space: while thinking about the "how" of putting my new shelves into my room I had the vision of a tower for room, that is high and uses less room on the bottom. I saw a wonderful lighthouse in the beginning of my small interest, but I didn't found the same, but this one on flickr.
and: I found that it is a kit I could buy and try to build of my own, the price is okay I think. It would fit wonderful in the corner of my room beside the window. I would try to make bigger windows or a conservatory -we will see.
here is the link to the company in germany which sells this "greenleaf"-product.