Preheat oven to 350°F (175°C).

Grease and flour a 12-cup fluted tube pan.

In a large bowl, cream together sugar and butter until light and fluffy.

Add vanilla and eggs, one at a time, beating until well blended after each addition.

In a separate bowl, combine flour, baking powder, salt, and orange peel.

Add the dry ingredients to the wet ingredients alternately with the sour cream, beating well after each addition.

Pour batter into prepared pan.

Bake for 55 to 65 minutes, or until a toothpick inserted in the center comes out clean.

Cool in the pan for 15 minutes.

Invert onto a serving plate and cool completely.