Combine 4 cups sugar, lemon juice, and water in a medium saucepan. Bring to a boil, and allow to boil for 10 minutes. Add rosewater and bring to a boil. Remove from heat immediately. Allow to cool.
Preparing Dough and Filling
Combine 1/2 cup sugar and nuts in a bowl. If using walnuts add cinnamon. Preheat oven to 300.
Unroll dough and cut into 9x12 pieces to fit into dish.
Grease bottom of 9x12 pan with butter. Place two sheets of dough in the baking dish. Brush dough with butter and repeat until half of filo dough is used.
Spread about 1 cup of nut mixture over the last layer of dough. Place two sheets of filo dough and brush with butter.
Repeat until nut mixture is used. On the final layer of filo dough, be sure to brush with butter.
Cut into 3 inch squares. Then, cut each square in half diagonally to make triangles. Bake for 1 hour and 15 minutes or until golden brown.
Remove from oven and pour syrup over top of baklava and allow to seep and saturate it well.