Preheat the oven to 325°F (165°C) and grease and flour a 10-inch tube pan.
Cream together the butter and sugar until light and fluffy.
Beat in the eggs one at a time, mixing well after each addition.
Combine the flour and baking soda in another bowl; gradually add this dry mixture to the creamed butter mixture alternately with the buttermilk.
Stir in the lime juice and lime zest until well combined.
Pour the batter into the prepared pan.
Bake for 60-70 minutes or until a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for about 10 minutes before removing it to a wire rack to cool completely.