Somewhere on the Town Hall square there is a small circular stone embedded in the ground. Most of us don't even know about it. So if you're a tourist, introduce it to locals :)
If you do manage to find it (good luck with that), then stand right on top of it. If you did everything right and found the right stone (there's a couple of fakes nearby) you "should" be able to see five of the most famous spires in Tallinn. If you stretch.
There is a hole in one of the roofs, purpose designed so you can actually see five spires instead of four!