Sheathed in white travertine marble and visible from miles around the city, San Francisco's third Catholic cathedral (1971) resembles a giant washing-machine agitator. It was designed by Pier Luigi Nervi & Pietro Belluschi, with McSweeney, Ryan & Lee.Enter through the main doors facing Geary Boulevard to see the bronze overpanel, an image of Christ rising above human figures to represent the ecumenical search for God throughout civilization. Backed by stained glass, the overpanel is also impressive when viewed from the interior.The building's most daring design attribute is its reinforced concrete cupola, formed of hyperbolic paraboloids that join to enclose a soaring atrium. At the level of the congregation, clear glass panels afford fine views of the city. Unobstructed views of the massive marble altar can be had from all 2,400 seats. Narrow stained-glass windows rise steeply from the four compass points to meet at the cupola's apex, forming a brilliant cross 190ft above the sanctuary floor. Suspended on wires 75ft above the altar is a contemporary baldachin, a shimmering canopy of anodized aluminum rods designed by Richard Lippold to sparkle in the slightest breeze. A magnificent, 4,842-pipe Ruffatti organ perches on a concrete pedestal. Cast-bronze shrines by Enrico Manfrini and Mario Rudelli depicts events in the lives of Mary and Jesus.