1. In a large mixing bowl, combine rye flour, all-purpose flour, caraway seeds, and salt.
2. In a separate bowl, dissolve sugar and yeast in warm water. Let it sit for 5 minutes until frothy.
3. Pour the yeast mixture into the flour mixture. Stir until a dough forms.
4. Knead the dough on a floured surface for about 10 minutes until smooth and elastic.
5. Place the dough in a greased bowl, cover, and let it rise in a warm place for 1 hour or until doubled in size.
6. Preheat your oven to 375°F (190°C). Punch down the dough and shape it into a loaf. Place it in a greased loaf pan.
7. Bake for 30 minutes or until the bread sounds hollow when tapped.
8. Let the bread cool on a wire rack before slicing.