You can do it with Bryce. Take a cylinder primitive, elongate it to the shape of the arch top. Change it to a negative. Take a cube prim, and shape it to the lower part of your arched window. Change it to a negative. Mate the two parts until they give you the RED shape in your pic above and GROUP. Turn your wall to positive and interesect your new negative cylinder/cube shape. Now GROUP again and you should have an arched shaped hole in your wall. I hope this helps. Regards The Bryster. (Chris)