A group of engineers and technicians studied Landowski's submissions and felt building the structure of reinforced concrete (designed by Albert Caquot) instead of steel was more suitable for the cross-shaped statue. The concrete making up the base was supplied from Limhamn, Sweden. The outer layers are soapstone, chosen for its enduring qualities and ease of use. Construction took nine years, from 1922 to 1931 and cost the equivalent of and the monument opened on October 12, 1931. During the opening ceremony, the statue was to be lit by a battery of floodlights turned on remotely by Italian shortwave radio inventor Guglielmo Marconi, stationed away in Rome but because of bad weather, the lights were activated on-site.