Go to your craft store and get Popsicle sticks and some craft glue. That should work to give you the shape. Paint it white. Use paper rolls for the columns and paint them.
It depends on what you want to build it with. I would recommend Popsicle sticks. You just glue them together until you make a square, and then for the roof you can build a stair case sort of...
You can make a model by using pieces of wood or cardboard or any material really, just make a sketch on what you want your model to look like, break it down to the main components and start the...