Well evidently the attachment worked, so here's an explanation:
Forgive the crudeness of the photoshop cloning on the image, but it doesn't need to be a masterpiece for you to get the idea...
In any photo you take, the horizon will always be at eye level. Anything below that level you will obviously be looking down on, anything above it, you'll be looking up at. This means that on my version of your picture, the upper yellow disc represents you looking at the underside of the top 'circle' of your tower, the roof if you like. Obviously, the lower yellow disc will be its floor. You can see from the (very rough) red grid that I've drawn that all the parallel perspective lines are meeting at the horizon at the 'vanishing point'. What this all means is that you need to have a picture of your tower from a perspective which matches this and the grid I drew should help you to determine this.
Hope this helps and sorry if I'm telling you stuff you already knew
