By 1919, Shahan and McKenna chose architectural drawings by the Boston firm of Maginnis & Walsh for construction of the national shrine. Initially, they considered a traditional Neo-Gothic architectural style, but Shahan opted instead for a Byzantine Revival-Romanesque Revival design. Cardinal James Gibbons, archbishop of Baltimore, blessed the foundation stone on September 23, 1920. More than 10,000 people attended the Mass, including ambassadors, government officials, and military officers. In 1929, the Great Depression halted the construction above the Crypt Church level. The beginning of American involvement in World War II stalled plans even further.