A short time later in 1930 Adler Planetarium was built, and in 1933–34 the island was at the center of festivities at the "Century of Progress" World's Fair. Taking part in the Century of Progress Exposition, 24 Italian Savoia-Marchetti S55X flying boats, under the command of General Italo Balbo, make the first transatlantic formation flight between Italy and Chicago. Only flying boats could be used because Chicago did not yet have a suitable nearby airport, except for Grant Park, which was occasionally used as a landing strip. Local publishing mogul Merrill C. Meigs supported earlier recommendations for converting Northerly Island into an airport, but construction did not begin for numerous reasons, such as lack of funds during the Great Depression and WW II. Construction did not begin until after a competing proposal to host the United Nations Headquarters on the island was lost in 1946. The Works Progress Administration connected the island to the mainland via a causeway at 12th Street in 1938. During this period Northerly Island was full of paths and walkways as well as a beach at 12th Street.