Construction is progressing quickly at 200 Amsterdam Avenue, where a 51-story, 668-foot tall skyscraper will soon rise. When first announced, the building was to become the tallest skyscraper on the Upper West Side. That title was lost when Extell announced plans for 50 West 66^th Street, a particularly striking 775-foot tall residential building designed by Snøhetta. But even the area’s second-tallest is too much for local NIMBYs, and with excavation work on the project now making rapid headway, opponents have begun engaging in increasingly deranged efforts to hoist a wall of red-tape around the southern blocks of the Upper West Side.