It is the newest cathedral in the nation, and the most expensive in American history.
The $190 million, 224,000-square-foot complex replaces St. Francis de Sales, fatally damaged by the 1989 Loma Prieta earthquake.
When it opens in the fall of 2008, the cathedral will bring together two parishes, St. Francis and St. Mary's, also in downtown Oakland.
The structure is hewn from 26 110-foot curved Douglas fir ribs and 768 horizontal struts, spaced by 26 101-foot high laminated mullions. The curved supports are cemented at the root and held in place at the top by a steel ring; outward pressure exerts a third type of support.
The entire structure rests on a foundation of base isolators intended to protect the cathedral in an earthquake by giving it some flexibility of movement.