How long did it take to complete the 555-foot Egyptian obelisk, topped with a 3,300-pound marble capstone and a 9-inch pyramid of cast aluminum?

• 要建造这个高555英尺的埃及式方尖碑，上头还要加上重达3300磅的大理石顶盖，并且以9吋厚的铝来制作尖端的金字塔顶，需要花上多长的时间呢？