Correction: An earlier version of the story incorrectly said that the exhibit closes at the end of September. It ends Jan. 20, 2014. This version has been corrected.

In 1759, Samuel Johnson launched a letter-writing campaign against the design for a new Blackfriars bridge in London. The proposed span would have used elongated or elliptical arches, which infuriated the curmudgeonly and conservative Johnson, who preferred old-fashioned, semicircular arches, like the Romans built. Commerce depends on bridges, which should be built for strength, and the strongest arches — as any intelligent person can deduce — are semicircular, Johnson argued. Supporters of the elegant, flattened arches contended that they could be made more than adequately strong, but Johnson thundered back that reason, good order, beauty and the well-being of the realm all depended on the traditional rounded arch.

It’s easy to understand Johnson’s instinctive distrust of the flattened arch as you explore “Palaces for the People: Guastavino and America’s Great Public Spaces,” a fascinating exhibition at the National Building Museum. The show explores a building technique known as structural tile, which allowed designers to create arches, vaults and domes of miraculous lightness and grace. Many of this country’s most important structural-tile domes and vaults were built in Washington, D.C., and although they don’t seem sufficiently robust to withstand the force of gravity, they have held without fail, and contributed immeasurably to the grandeur of the capital’s public, democratic spaces.

Dominating U.S. architecture

The Guastavino family is one of the great, little-known chapters in American architectural history. Rafael Guastavino, the patriarch of this Spanish clan of builders and designers, came from Valencia, where for centuries builders had used thin tiles and fast-drying adhesive to create vaults and domes of astonishing thinness. The technique was at least as old as a letter written in 1382 in which the king of Aragon directed his court builders to learn this “very profitable, very lightweight, and very low cost work.” Guastavino, trained as a builder and designer (he never finished a formal architecture degree), learned the local method, and began extending its possibilities.

In 1881, he emigrated to New York with his son Rafael Jr. He had no English-language skills, but he had $40,000 in his pocket, and a great deal of self-confidence and marketing acumen. And he succeeded brilliantly, patenting various small improvements to traditional structural tile technique, selling its virtues to the most prominent architects of the day including McKim, Mead and White, Carrere and Hastings and Richard Morris Hunt. For more than half a century, he and his son dominated American architecture, contributing vaults and domes to Pennsylvania Station and Grand Central Terminal in New York, the National Archives, the Interior Department, the Cannon House and Russell Senate office buildings, and a host of others in Washington. With a virtual monopoly on the tile technique, they worked throughout the United States, building grand Beaux Arts buildings for cities, colleges, the military and, if you were a Vanderbilt, private residences, too.

The National Building Museum exhibition began last September in Boston, where it was organized in partnership with the Massachusetts Institute of Technology and first seen at the Boston Public Library (with vaulting by Guastavino, and the project that launched the family’s U.S. fortunes). It includes photography, architectural drawings, letters and documents and a tile vault built to demonstrate the technique for modern skeptics. It is a shallow-rise vault, spanning a square space, framed on four sides by gentle ribs. Quick-drying mortar made it possible to fill in the interior spaces fast, each tile — about an inch thick — clinging to its neighbors. The finished vault was made of several thin layers of tile, with the joints slightly staggered. It looks and feels more like frosting a cake than the older technique of carefully cut stone held in place by a wedge-sided keystone.

Masons from the International Masonry Institute and MIT students construct a half-scale vault inspired using traditional Guastavino design methods. The model is on display at the National Building Museum. (Courtesy National Building Museum, International Masonry Institute, MIT and Boston Public Library/The Washington Post)

The Guastavino system not only spanned large spaces rapidly and relatively cheaply, it also produced vaults that were strong enough to support the floor above them. Anyone who has attended a concert or lecture at Baird Auditorium, in the Smithsonian Museum of Natural History, knows the Guastavino look intimately. The auditorium is capped by a gentle dome spanning 90 feet, clad in colored, glassy tiles, leading to flattened arches on the side walls. The ceiling tiles, set in a herringbone pattern, seem to flow, as if applied decoratively to a hidden superstructure. Although the dome is only a few inches thick, it is strong enough to support the floor of the main atrium above.

Structural honesty

The Guastavinos succeeded for several reasons. According to John Ochsendorf’s “Guastavino Vaulting: The Art of Structural Tile,” the family arrived in the United States before building codes were established, when the main test of a technique was whether it could stand up to a load challenge. The family established close relationships with the major architects of the day, who were building impressive buildings, but didn’t have ready access to masons who understood the old, traditional vaulting techniques. Many architects resorted to wood lath and plaster dome-shaped shells, or used cast iron supports. Both techniques were susceptible to fire, while the masonry of the Guastavino system was essentially fireproof. When Thomas Jefferson’s rotunda at the University of Virginia burned in 1895, architect Stanford White hired the Guastavinos to rebuild it in tile.

The Guastavinos were adept at promoting their work, and for decades their company raced to stay ahead of design trends. When a fire ravaged Paterson, N.J., in 1902, they took pictures of damaged and destroyed buildings using older and non-fire-proof construction, and of one of their own domes, which survived the blaze. They placed advertisements in important architectural and building journals, detailing their technique and its advantages. And although they had an enormous (and unfair) advantage through vigorous patent applications, they were also innovators, creating among other things acoustical tiles to make academic, performance and meeting spaces less resonant.

They also built their own tile factory, in Massachusetts, vertically integrating their supply and construction process. While Rafael Sr. worked intuitively, making decisions based on long experience, Rafael Jr. worked to master the engineering details, and the company took on more and more complex work, including huge oval-shaped domes with large skylights and irregular spaces for which architects essentially left the Guastavinos to devise engineering solutions.

Their decades of dominance coincided with the City Beautiful movement in the United States, in which a progressive care for design and beauty was extended deep into the public realm. The Guastavinos designed vaults for bridges, highways and subways (including the ornate City Hall station in New York). The grandeur of these works still leaves one in awe, and a little ashamed of the shabby airports and purely functional bridges we build today.

Architects were particularly pleased with the tile vault method because it appealed to their sense of integrity in construction, that buildings should have “structural honesty,” rather than fake domes of wood and plaster. But that same sense of structural honesty would play a large role in the demise of the Guastavino fortunes in the 1950s and ’60s, as steel and concrete became the preferred method for covering large spaces. Although it was at first cheaper and faster than other forms of construction, tile vaulting was labor intensive and thus increasingly expensive. As early as 1934, when New York’s Hayden Planetarium (spanning 81 feet with a three-inch-thick dome of reinforced concrete) was built, it was clear that the Guastavino method would face serious competition from newer construction methods.

Out with the old

Building codes and increased engineering sophistication also worked against the traditional Guastavino method. Engineers, trained to work with steel and concrete, weren’t quite sure how to calculate the loads for a tile vault. In 1963, engineers removed much of the Guastavino work from New York’s Metropolitan Museum of Art, replacing it with steel construction, because they couldn’t determine the safety of the old method. As concrete took over, the Guastavino company was reduced in some cases to creating decorative rather than structural tile work.

And yet not one Guastavino vault has ever failed, according the curators of this exhibition. Many, alas, have been destroyed, or cruelly neglected, as buildings such as Detroit’s magnificent railroad station were abandoned.

Excellent photography and clear exposition make the exhibition a pleasure. Computer terminals with supplemental information don’t add much, and on one recent visit, a link for panoramic images brought up a blank page.

The sample vault, filling part of one room, does much of the work of explanation, yet it still seems as though it shouldn’t quite work. Even today, in which buildings routinely perform counter-intuitive structural stunts, the flat, thin Guastavino vaults leave one as skeptical as Johnson was about the Blackfriars bridge 250 years ago. To be fair, though, it should be noted that the Blackfriars bridge, finished in 1769, was poorly constructed, required extensive repairs and was replaced a century later.

Palaces for the People: Guastavino and America’s
Great Public Spaces

On view at the National Building Museum through Jan. 20, 2014. For more information, including admission charges, visit