In a large bowl, combine flour and salt. Cut in shortening until mixture resembles coarse crumbs. Stir in water until mixture forms a ball. Divide dough in half and shape into balls. On floured surface, roll from center to edges into 12 inch circle. Avoid rolling too thin.
Spread approximately 2 cups blueberries on each rolled pastry, or enough to make a single layer of blueberries leaving a 2 inch border. Sprinkle with cinnamon, sugar and slices of butter.
Roll pastry like a jelly-roll, tucking the ends as you roll, and place on a cookie sheet.
Bake in the preheated oven for 60 minutes, or until golden brown.