Preheat the oven to 325 degrees. Grease a 10-inch Bundt pan and set aside. Using a wooden spoon, or the paddle attachment of an electric mixer, cream butter and sugar together in a large bowl until fluffy and pale. Add eggs, one at a time, beating well after each addition, and scraping down sides of bowl.
Sift the flour, baking soda and salt into a small bowl. Add the flour mixture to the creamed mixture in 3 additions, alternating with buttermilk in 2 additions, beginning and ending with dry ingredients. Don't overmix; just fold gently until batter looks well blended. Fold in lemon zest and juice. (Batter may appear curdled with addition of lemon juice - don't worry!)
Scrape the batter into the prepared pan, smoothing top with a rubber spatula. Bake the cake for 1 hour to 1 hour 15 minutes, or until a tester inserted in center comes out clean, and cake has begun to pull away from sides of pan. Transfer the pan to a wire rack and cool for 10 minutes.
Meanwhile, prepare the glaze. In a medium sized bowl, cream the butter until light and fluffy. Gradually beat in the sifted sugar and combined zest and lemon juice, alternating one then the other, until a creamy, pourable consistency is achieved.
Invert cake onto a wire rack over a baking sheet. Spoon glaze over hot cake and cool completely before cutting. Best the day it is made, it will keep fairly well, in an airtight container at room temperature, for up to 3 days.
Makes 10-12 servings