In a large bowl, stir together the flour, yeast, salt, and fresh rosemary. Add the water and olive oil, stir together with a wooden spoon or silicon spatula until all of the flour is moistened, about 1 minute. The dough will look somewhat shaggy. Cover the bowl with plastic wrap and let rest at room temperature (preferably a slightly warmer room) overnight or 12 to 18 hours.
Lightly flour a work surface and turn the dough out onto it. Sprinkle it with a little more flour and fold the dough over once more. Place it back in the bowl and cover it with plastic wrap once more and let sit for 2 more hour. It will rise almost double in size.
30 minutes before the dough is done rising, place a large 6 to 8-quart Dutch oven in the oven and preheat to 450 degrees F.
When the dough is finished rising, use floured hands to shape the dough into a ball and place it onto a piece of parchment paper.
Remove the Dutch oven from the oven. Lift the edges of the parchment paper with the dough on it and carefully transfer it into the heated Dutch oven. Cover with a lid and bake for 30 minutes. Remove the lid and continue to bake for an additional 15 to 30 minutes, until it forms a crunchy, golden crust. Cool on a wire rack for at least 5 minutes. Serve warm or at room temperature.
