Columbia Firehouse, a two-tiered American, will stake out the historic Old Town space currently occupied by Bookbinder's when that Philadelphia-sired, high-end restaurant closes at the end of May. The handsome ground floor, with its plant-filled atrium, will serve an affordable casual menu, while upstairs there will be traditionally inspired steak and chophouse fare. Neighborhood Restaurant Group, of Buzz, EatBar, Evening Star Cafe, Rustico and Vermilion fame, is behind the new venture, which plans to open in July (109 S. Saint Asaph St.).