I couldn't resist this Romanesque fortified church when I saw it on Pierre Gauriat's excellent site Maquettes en Carton:
Card Models / Maquettes en carton
It's in 1:400 scale, so it makes up into quite a small model - right up my street. It was a bit of a pain to put together as some of the parts only fitted where they touched. I'm glad I persevered with it though as it made up into a pretty little thing, I think.