I made one for my niece's 4th birthday - unfortunately I'm still waiting for my sis to send me a photo, but it turned out really well.
I made 10" round and a 6" round madeira sponge cakes and filled them both with jam and buttercream, then got 2 swiss rolls (M&S do a good one) and cut one of them in half for the towers (in half lengh-ways to get 2 tall thin cylinders iyswim) and cut the other one to get a 'fat' round tower for the top of the cake.
Spread thinned down buttercream (I thin with milk) all over the cake to give a crumb crust, then cover with fondant coloured accordingly (mine was yellow as that's DN's fave colour).
Use a ruler/skewer/thin metal edge, indent the sides of the cake all the way around to make 2 to 3 horizontal lines for the 'bricks' (I have a turntable, made it easier but you can do it by hand just as well if you go carefully) and then do the vertical lines by pressing in with a cocktail stick/sharp knife point.
Once all the bits are covered and 'bricked' use water icing to glue the two towers to the front sides of the cake and the fat tower to the top of the cake. I used waffle cones covered in gold lustre spray for the tops of the towers, cemented them on with icing and then tarted the outside edges up with rosettes of icing and jelly tots to hide any ragged bits.
I cut out brown coloured fondant in an arch shape for the door and made 'bricks' of leftover yellow fondant for the surrounding architrave. Did the same with white fondant for windows in the towers, outlined in black writing icing to make window panes.
Then I got an icing bag full of pale green royal icing (the ready mix stuff) and piped ivy-ish straggly vines randomly up the walls/over the windows (helps to hide a great many joins/cracks/bits where you've gone wobbly!) and added sugar flowers.
It looked really effective and didn't take too long either. I just wish I had a photo to show you!