In 1881, a Spanish builder named Rafael Guastavino immigrated to the United States with no job, no family awaiting him and no grasp of English. He did possess one valuable piece of knowledge, however: Guastavino had learned a technique, unknown in the United States, for building large structures, such as decorative arched ceilings, that were both lightweight and fantastically sturdy.Within a few decades, the family firm Guastavino founded had helped design and construct many of America’s most famous civic monuments: the arrival hall at Ellis Island, New York’s Grand Central Terminal and its old Penn Station, the Boston Public Library, the Biltmore estate in North Carolina and the National Museum of Natural History in Washington, among others.Yet even though famous architects frequently employed Guastavino and his son — who eventually took over the family business — the family’s contributions were rarely noted. Millions of Americans have walked through Guastavino-built stations, libraries and museums without having the slightest idea who was responsible for their grand, soaring interiors.John Ochsendorf, an associate professor of building technology in MIT’s School of Architecture and Planning, would like to restore the Guastavino family to its rightful place in architectural history. Ochsendorf’s new book, Guastavino Vaulting: The Art of Structural Tile , published this month by Princeton Architectural Press, is a richly illustrated survey of the clan’s achievements, with a twist. A trained engineer, Ochsendorf also explains how such improbably thin arches could be so strong and durable. No Guastavino building has ever collapsed.“This one family of immigrants built many major American monuments,” says Ochsendorf. “Yet we’re trying to rescue them from anonymity so we can celebrate and understand their achievements. As a structural engineer, I’m fundamentally interested in how their vaults stand up and how they built them. That’s the magic at the very heart of the story.”As an architect in Spain, Rafael Guastavino learned a centuries-old regional building technique, using interlocking layers of thin brick tiles held together with mortar to make large, curving interior features such as domes, vaults, arches and spiral staircases. These structures could be built cheaply and were fireproof.Several years after Guastavino moved to America, hoping to better his financial prospects, he was asked to build the interiors of the Boston Public Library. The attention Guastavino received for the landmark library led to other important commissions, even after he died in 1908 (his son, also Rafael, took over the firm). Guastavino family works include several majestic train terminals, state capitols, interiors of Harvard’s Widener Library and more than 200 structures woven into the architectural fabric of New York City.“The Guastavinos not only built their vaults, they designed them,” says Ochsendorf. “Architects … would send them drawings with a blank space saying, ‘Guastavino here,’ and the Guastavino company would design the form and the decorative patterns and colors.”The Guastavino influence finally declined after 1930, when the lean, straight-line architecture of the International Style began replacing the opulent Beaux-Arts fashion that allowed room for curvilinear flourishes. In the 1960s, scholars rediscovered Guastavino buildings (which are almost always unmarked as such) and noted their stylistic links to Spain; Ochsendorf’s book synthesizes research from Europe and America.“It’s a very important work that brings back a major, major contribution to American architecture and construction,” says Richard Guy Wilson, chair of the Department of Architectural History at the University of Virginia. “You can go virtually anywhere in the United States and find the Guastavino system in use.”Ochsendorf also explains how the Guastavino structures have resisted gravity’s pull, even though they employ brittle materials in large, curved constructions. “The fundamental character of masonry is that it is very strong in compression but very weak in tension,” says Ochsendorf. That is, compression is a pressing force, so bricks stacked atop one another can form a strong structure. But tension is a stretching force, so an arch or dome made up of bricks is vulnerable; it must resist forces pulling the pieces apart. The gradual, shallow curves of a typical Guastavino ceiling help distribute forces across the ceiling, compressing the tiles laterally into one another and limiting tension.The elder Guastavino, Ochsendorf notes, perpetuated the mystique that he possessed secret construction techniques. The Guastavinos opened their own tile factory in Woburn, Mass., and held numerous patents, enhancing the idea that they had a unique building recipe. But Ochsendorf argues that the Guastavino secret was not in the substance or interlocking patterns of their tiles, but the form of their structures. “The strength of these Guastavino structures depends on their shape, not the strength of their material,” says Ochsendorf.Consider the Boston Public Library’s interiors, which were built with bricks that Guastavino did not choose, and feature eight different brickwork patterns. If Guastavino’s success depended on materials or brickwork designs, those interiors might be suspect, but they can sustain a floor load over three times the library’s current demands.“Overall, the Guastavino company really found good forms for compression that allow for significant long spans to be built,” says Ochsendorf. “And they developed this to the point where you scratch your head and say, ‘I’m not sure how that stands up.’”Studying Guastavino structures is no idle fascination for Ochsendorf, who teaches classes on masonry construction and has built Guastavino-influenced structures. These include South Africa’s award-winning Mapungubwe National Park Interpretive Center, a sprawling structure with domes made from local soil tiles. In this vein, the Guastavino buildings “form a living tradition,” he says, inspiring architects and engineers to incorporate locally available, low-cost materials.“It’s part of our responsibility as engineers to study our own history,” says Ochsendorf. “To appreciate where we are as a profession today, we need to understand who our heroes are and why their works are great.”