Preheat your oven to 350 degrees Fahrenheit. Grease a 10-cup bundt pan thoroughly.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a large mixing bowl, cream together the butter and granulated sugar until fluffy.
Add the eggs one at a time, mixing well after each addition.
Mix in the sour cream, buttermilk, and lemon zest until combined.
Gradually add the dry ingredients to the wet ingredients, mixing until smooth.
Pour the batter into the prepared pan and bake for 55-60 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 30 minutes, then transfer it to a wire rack to cool completely.