Toy Blocks Cathedral
(Enlarge by holding "Ctrl" and scrolling your mouse)
A variation on The Walker Book Cathedral. We've added a few things, but a child with the Walker Set (Beginner Set W) should be able to make this except for the roads. Note that this shows the typical way of styling roofs in block buildings. With building blocks, roofs are rarely planked as the planks fall off. If you are determined to cover a roof, the way to do it is to cut out a sufficiently large piece of cardboard, score it down the middle, fold it in half and set it on the joists like a hat. Do the scoring with a dull kitchen knife just enough to indent the cardboard. Paper has a grain, incidentally, and this will be easier to do in one direction than in the other.
We also make flying buttresses and sooner or later we will build a cathedral that uses these quintessential parts of Gothic Architecture. It takes time to make these things work, however, and all building design is accompanied by a lot of do and redo. I bet real architects have the same problem. "Oops!"