However, construction of the exterior, including the twin towers on the west facade and the flèche at the crossing, was not completed until 1951,[5] coinciding with the 250th anniversary of Detroit's founding.

The building's exterior is made of Ohio sandstone, with Indiana limestone used for buttress facings, traceries, and doorways.

Changes included a plaza on the north side of the structure, reconfigured interior spaces, a new sanctuary, cathedra, baptismal font and organ.

[9] Although Pope John Paul II's 1987 visit to the United States originally included only stops in the southern and western parts of the country, Detroit's cardinal archbishop, Edmund Szoka, campaigned for him to include the Detroit area.

In addition to Archbishop Szoka's personal appeal, the Vatican realized there was no scheduled meeting with permanent deacons, and the Pope would not have given a major address on social justice, which he did at Hart Plaza.

[citation needed] The Pope arrived in Detroit on September 18, 1987, and spoke before large crowds in Hamtramck, to permanent deacons from across the United States at Ford Auditorium, adjacent to Hart Plaza and the Pontiac Silverdome.