1. Preheat oven to 400 degrees F.
2. Arrange half the lemon slices in a single layer in a baking dish. Layer with 2 sprigs of rosemary, and top with salmon fillets. Sprinkle salmon with salt, layer with remaining rosemary sprigs, and top with remaining lemon slices. Drizzle with olive oil.
3. Bake 20 minutes in the preheated oven, or until fish is easily flaked with a fork.