Completed in 1942, which dam on the Columbia River contains about 12 million cubic yards of concrete?

Completed in 1931, which building rises more than 1,400 feet at 350 Fifth Avenue in New York City? Completed in 1932, which monument bears the inscription "Here rests in honored glory an American soldier known but to G… Completed in 1937, which hiking trail of about 2,000 miles passes through 14 states? Completed in 1937, which bridge cost about $35 million to build? Opened in 1955, which bridge crossed the Hudson River near Nyack, New York? Completed in 1965, which monument towers 630 feet over St. Louis? The Sultan Qaboos Grand ___, completed in Muscat, Oman, in 2001, welcomes non-Muslim visitors. What kind of building is… Completed in June 1854, the lighthouse on which San Francisco Bay island was the first active one on the U.S. West Coas…