Sift the flour, baking powder, sugar and salt into a large mixing bowl. Add the butter to the bowl and use a pastry cutter or a fork to cut the butter into the flour. Do this until the mixture resembles rough crumbs and the butter is still in pieces.
Add the buttermilk and stir with a wooden spoon until a loose, sticky dough forms.
Turn the dough out onto a clean, lightly floured surface. Use your hands to shape the dough into a rectangle. Fold the dough over and reshape again into a rectangle about 1½-inches thick.
Cut the dough into biscuits by pressing straight down, using a 3-inch biscuit cutter. Reshape the dough as needed to continue cutting biscuits.
Place the biscuits on a greased cookie sheet and bake until golden brown, about 15 to 20 minutes.