The plan specified that most streets would be laid out in a grid. To form the grid, some streets (later named for letters of the alphabet) would travel in an east–west direction, while others (named for numbers) would travel in a north–south direction. Broader diagonal grand avenues, later named after the states of the Union, crossed the north–south-east/west grid. These "grand avenues" intersected with the north–south and east–west streets at circles and rectangular plazas that would later honor notable Americans and provide open space.