Light and Shadow

Volume 42, Issue 1 :: by Craig W. Hartman, FAIA

Civic Space, Sacred Space, and the Cathedral of Christ the Light

If each work of architecture must bridge past, present, and future – and all of the particular social and cultural dimensions embedded within – then a new Catholic cathedral, set in a relatively young and very culturally diverse city in California, provokes especially profound questions.

How might a cathedral, conceived in the 21st century, within a rapidly changing Pacific Rim setting, possess the cultural integrity and the power to inspire that define the great European cathedrals? How might a new cathedral speak to contemporary culture while honoring two millennia of Christian tradition? And more specifically, how might this new cathedral provide a meaningful setting for both spiritual renewal and civic discourse in its immediate community, the city of Oakland?

The historic St. Francis de Sales church, originally completed in 1893, had served as the cathedral for the Diocese of Oakland from 1962 (when the diocese was established) until it was rendered unusable in the 1989 Loma Prieta earthquake. After much reflection, the diocese, which serves more than 500,000 Catholics in two counties east of San Francisco, resolved to build a new cathedral center, overlooking Lake Merritt in downtown Oakland, that would include the 1,350-seat main cathedral sanctuary along with a mausoleum, a conference center, administrative offices, bishop’s and clergy residences, a bookstore, a café, and community-serving ministries.

A lengthy international selection process, culminating in a design competition, led to the initial selection of Santiago Calatrava as the architect for the new cathedral. After a year of studying various sites, however, the architect withdrew from the project. The Diocese then turned to the original competition design by Skidmore, Owings & Merrill.

This vision was initiated under the leadership of Bishop John Cummins, the second Bishop of Oakland, and completed under Bishop Allen Vigneron, who succeeded Bishop Cummins in 2003. Both were passionate advocates for a cathedral that would speak to the community in the architectural language of our time. Bishop Vigneron and a task force of Catholic scholars helped to develop the nuances of this language in relationship to the Catholic liturgy.

Simple Elements

In considering a design that would honor the most elemental qualities of human spiritual experience, it seemed appropriate to reflect on the very beginnings: the account of the Creation beginning with light, water, earth, and trees, followed by living creatures and finally humankind. If these elemental qualities could be shaped to celebrate the fundamental rites and tenets of the Catholic faith – Baptism, Reconciliation, and the Eucharist – a space that would nurture spiritual journeys on a personal, individual level might emerge. Such a cathedral would embody the most ancient of earth’s materials – the same that defined architecture at the time of Moses, Solomon, and eventually Jesus – and these “of the earth” materials would be shaped to receive and celebrate the presence of light.

From this perspective, light is a sacred phenomenon, and its introduction within the cathedral is perhaps the most visible manifestation of God’s presence. The search for the poetic expression of light has largely defined the architectural history of the Catholic Church. In this search, the church has embraced the most advanced architectural thinking to create works of architecture that illuminate, inspire, and ennoble the human spirit. One need only experience the impossible lightness of Sainte-Chapelle’s stone structure, the Euclidean clarity of Chartres Cathedral, or the domes of Brunelleschi and Bernini to understand the importance that innovation has played in shaping the church’s architectural traditions.

For a 21st century cathedral set in a dense, diverse city, the invocation of elemental qualities also provides a means for honoring the church’s 2,000-year history without forcing a culturally biased point of view. The design of the Cathedral of Christ the Light strips away received iconography, allowing the more essential experience of light, materials, and space to instill a sense of sacredness that is approachable and open to the region’s evolving multicultural population.

Sacred Geometries

The cathedral’s plan geometry lends itself to the “ring” advocated in Rudolf Schwarz’s seminal 1938 book Vom Bau Der Kirche, translated in 1958 as The Church Incarnate. Schwarz, a friend and colleague of Mies van der Rohe, proposed that the arrangement of congregants in a circle around the altar should create a sense of community and inclusion. The changes in the Catholic liturgy brought by Vatican II in the mid-1960s reinforced this plan in contrast to the linear, hierarchical plan of early cathedrals.

The design began with two intuitive ideas. First, the architecture should be soft, fluid, and ephemeral in response to its place on the lake and the Pacific Rim. Second, for practical and metaphorical reasons, the sanctuary should be formed of wood. Wood can be shaped easily and is a cost-effective, renewable resource. With the proper cross-section, it is fire-safe and can retain its structural soundness for centuries. Metaphorically, wood is associated with biblical stories ranging from the ark to the temple and is also associated with places of sanctuary and dwelling – both modest and noble – in the collective human memory.

Sketching a conceptual plan revealed that the sanctuary could be given geometric structure through the intersection of two great arcs. The resulting interlocking circles create at their intersection the Vesica Pisces form within the cathedral’s plan. This shape evokes the symbol of a fish – an ancient symbol of congregation and a sign of Christianity.

The curved plan form is further developed in the third dimension by the intersection of two spheres, which define the building’s principal structure and volume. The Vesica Pisces recurs above – defining the cathedral’s luminous ceiling – and marks the position of other key points within the cathedral, most notably the Eucharist tabernacle and the Baptismal font. In section, the south-facing Alpha Window, the Vesica Pisces ceiling, and the Omega Window establish a circular geometry – also a sacred reference for many cultures – that suggests the cycle of birth, redemption, and death.

The Fibonacci sequence – a geometry often linked with organic systems and natural phenomena – defines the detailing and proportioning of the Reliquary Wall, which forms the cathedral’s base. The 15-foot-tall cast-concrete wall – 12 feet wide at the base, tapering to 9 feet at the top – expresses a weight and mass that are clearly anchored to the earth. Side chapels “carved“ into the mass provide discrete spaces for spiritual reflection and culturally specific icons and art. Inspired by Ronchamp, these side chapels are sliced with narrow openings that allow light to rake the walls and floors.

Lightness and Luminosity

The primary building elements each work to shape the experience of light within the cathedral. The delicate, Douglas fir structure comprises 26 laminated ribs joined by angled structural louvers that become progressively more open as they layer upward to the top of the vault. Each louver reflects daylight onto the bottom face of the panel above, resulting in a softly luminous interior wooden vessel enclosing the sanctuary. At night, this quality is reversed when the inner vessel, illuminated from within, takes on a lanternlike presence.

The spherical segments of the sanctuary are held within two conical segments of glass. The conical and spherical geometries are concentric at the base and move apart as the building meets the sky. The conical segments are expressed as veils of ceramic frit-coated glass floating beyond the inner sanctuary vessel, enclosing and protecting the interior. The fritting creates a tapestry of clear, translucent, and opaque glass that captures the shifting daylight and produces a quietly dynamic pattern of light and shadow within the sanctuary.

These two geometries – the cone and the sphere – are laced together with a system of compressive wood struts and delicate steel-tension rods. Together they form a high-strength composite structure of extraordinary lightness. The margins at the north and south ends are enclosed in highly transparent, low-iron glass to reveal the connecting structure and to allow light to strike the inner conical surface, causing the translucent glass to become a glowing veil.

Rising 100 feet above the cathedral’s entrance, the Alpha Window consists of triangular aluminum panels that diffuse direct southern daylight. Here, words draw from scripture to reveal meaning: “I am the Alpha and the Omega, the first and the last, the beginning and the end.“ Passing through the entrance and under the Alpha Window, visitors cross the sanctuary’s open and ethereal nave. Daylight streams downward from the Vesica Pisces-shaped oculus ceiling that tops the structure. The ceiling’s concave diagrid of porous aluminum floats below a convex glass surface, capturing and modulating the changing sunlight throughout the day. A glass ring set in the floor around the square, white marble altar extends this light to the catafalque, or altar, in the mausoleum below. (The circle and square also refer to the Asian symbol for heaven and earth.)

Behind the altar, within the Omega Window, a depiction of Christ from Chartres Cathedral is transformed and rendered in anodized aluminum panels and 94,000 pixel-like perforations. The powerful presence of the 58-foot-tall image relies simply on the play of light penetrating the different-sized perforations, which were created using a proprietary digital algorithm. Points of light shine through the holes, which were set in 100 different diameters, revealing the image and providing a nuanced sense of depth. Through the filter of contemporary technology, the original content – a sculptural image from the 12th century – is transformed into an ephemeral veil of light and shadow in the 21st century.

Porosity, Connection, and Sustainability

Complementing the simple use of light and materials is an underlying porosity that connects the cathedral center’s various components and knits the complex into the surrounding city. The site is unconditionally open and welcome to all, regardless of faith. Like Cluny, it seeks to weave together indoor and outdoor rooms and gardens as an overall precinct offering places for respite, reflection, and meditation. Unlike early monastic complexes, however, the design creates a very porous condition that is linked to the city in every direction and serves to mediate the topographic shift downward to the lake’s edge.

Within the cathedral sanctuary, openings penetrate the full depth of the Reliquary Wall on axis, with each aisle radiating from the altar, flooding the aisles with light and creating a visual link between the altar, the city, and the lake. Elsewhere, skylights and a below-grade courtyard bring natural light and landscape into the offices and conference room areas below the plaza level.

With its elemental qualities, crafted with advanced technology and practices, the cathedral is inherently attuned to nature, thus minimizing the building’s ecological footprint. The entire cathedral complex is constructed of modest, regionally available materials, including resource-conserving slag and fly-ash concrete and sustainably harvested Oregon Douglas fir.

The thermal mass of the cathedral’s base helps to reduce rapid heat gain, while heavier pools of cool air introduced through openings in the sanctuary floor displace warm air and cool the lower, occupied strata of the expansive volume. When needed, comfort is provided by warm water circulating within the concrete floor – a Roman technique. The low-E glass enclosure, working with the interior vessel, modulates daylight and heat gain within, and limits the need for artificial lighting to evening hours.

The Douglas fir ribs and louvers provide protective structural elasticity and favorable acoustical conditions. An advanced seismic system, which includes base isolation, is designed to withstand a 1,000-year earthquake, preserving the cathedral for centuries.

The most significant challenge in creating a work of architecture intended to stand for centuries is not a technical question but a cultural one. The aspiration was to make a cathedral that is enduring in its worthiness, one that, in this relentlessly secular world, will provide respite, inspiration, and cultural meaning for untold generations.

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