Photo courtesy Louis I. Kahn Collection, The University of Pennsylvania Historical and Museum Commission
Louis I. Kahn’s Trenton Bath House holds an outsize place in the history of modern architecture. It was built in 1955 to serve a community center swimming pool outside the New Jersey city. In its design, some of the renowned architect’s most influential ideas coalesced. “I discovered myself after designing that little concrete block bathhouse in Trenton,” Kahn would say in a 1970 interview. Its planning principles are of great use in house design and appear to have evolved from the tradition of prototype houses. The photo of the newly completed Bath House above, taken by Kahn’s office, highlights its primitive power based on primary shapes. The building’s pyramid roofs are truncated to create sky openings that recall the temple space of the Pantheon. The circular pebble garden in the foreground has a mystical resonance. It may also mark the source of the Bath House’s lineage as the 16th century Villa Rotunda.
Andrea Palladio’s Villa Rotunda adopts the symmetry, porticoes and triangular pediments of ancient temples. It is unique among Palladio's villas in having a temple portico on every facade. The architect's use of such features in Renaissance villa designs of the late 1500s influenced the shape of houses through 18th century English manors to 21st century American housing tracts. Palladio was dedicated to classical precedents but lived before the rediscovery and excavation of the ancient house in Pompeii. He made his own assumptions about residential design in antiquity, arguing that the surviving temples of the Romans must have evolved from their vanished homes. These houses would thus have been scaled-down temples. This contradicted descriptions by historical sources like Vitruvius, but conveniently allowed Palladio to indulge his temple-class spatial aspirations and composition skills on original villa designs, without denying them a claim to a classical pedigree. Pompeii’s rediscovery in 1599 showed that ancient homes were low-slung courtyard houses free of pediments and porticoes. America’s White House and countless other Palladian spin-offs are thus based on a historical misconception. Palladio’s hugely appealing house forms would start a history all their own.
Palladio’s villa designs make up the second of his Four Books of Architecture and might be called one of the very first house plan books. Palladio’s treatise has been the greatest single influence on Western architecture since its publication in 1570. Thomas Jefferson called it “the Bible,” and was guided by it in designing Monticello and the University of Virginia. As illustrated in the Four Books above, Palladio’s Villa Rotunda has a double-height central hall with a circular plan ordained by the dome which crowns it. This main space is surrounded by smaller, subsidiary one-story rooms, and then porticoes and outside stairs in a cruciform pattern radiating from the central circle. The house stands on a hilltop and its exterior stairs further elevate its main level, from the center of which there are views outside in all directions. The roughly triangular masses between the circular center room and its square outer frame add structural support to the dome above. They are also hollowed out to contain four stairs. This keeps the stairs from disturbing the pure forms of the other rooms or the symmetrical ideal of the house. They fall within the wall thickness, the “poché,” to use the French architectural term for this typically shaded zone into which pockets of support space are sometimes carved. This stair solution is both practical and part of a much loftier agenda. Palladio scholar Robert Tavernor, in his 1991 book, Palladio and Palladianism, has commented on the villa’s square-inscribed central circle:
The circle was the Pythagorean symbol of unified perfection, infinity and deity: indeed, it symbolized virtue to the early Christians. The square, conversely, was equated with the physical universe and the material world. Attempts at ‘squaring the circle,’ from the Pythagoreans onward, reflect the desire to reduce infinity to something finite, or to transmute the divine to the physical realm. What could be more appropriate for the Villa Rotunda, which with its perfect natural setting, outward symmetry and temple-like appearance comes closer than any other to Palladio’s ideal for the villa?
The Neo-Palladian architect Colen Campbell published his own influential architectural treatise, Vitruvius Britannicus, in the early 18th century. It chronicled two centuries of British architecture and promoted Palladianism. The collection included Campbell’s own enlarged update of the Villa Rotunda, Mereworth Castle, built in Kent, England, in 1723. Its upper floor plan is at left above, and its main floor at right. Campbell retained Palladio’s focal squared circle, but filled only two of its hollowed corners with stairs, making bedroom closets of the other two, and, on the upper level, a passage into the rotunda gallery. His varied use of these spaces has implications for the design’s potential as a prototype. Pre-loaded into a model house diagram, such flexible cavities might absorb alternate or evolving services with no effect on the formal spaces which the design is primarily about.
Campbell’s contemporary, James Gibbs, published A Book of Architecture in 1728. It presented his own built and theoretical designs as examples “of use to such gentlemen as might be concerned in building, especially in the remote parts of the country, where little or no assistance for designs can be procured.” The book was thus at once a monograph of Gibbs’ work and a pattern book of prototypes. Plate 44 of the book, above, shows a model “House made for a Gentleman.” Its idealized plan is like that of the Villa Rotunda, but arranged into a nine-square tic-tac-toe grid with a strong cruciform undercurrent. The squares to the right and left of the central hall are precisely dedicated to service rooms and circulation. Palladio’s central circle is here rendered an octagon, and in the corners around it where Palladio buried stairs, Gibbs places short, shunting corridors to give his gentleman’s servants direct, screened access from the support areas to each of the main rooms. Gibbs’ plan makes for such a decorative visual pattern that its basis in a master-servant social order and discrete servicing might escape notice. His section drawing through the house emphasizes the central hall's primacy, a master space shaped and supported by the spaces around it.
A garden pavilion from Gibbs' book closely follows the example of centrally planned Renaissance churches like Giuliano da Sangallo's Santa Maria Delle Carceri. Its boxed circle within a Greek cross could also be the kernel of the Villa Rotunda and its offspring.
In his design for the Trenton Bath House, Kahn seemed to pick up Gibbs' thread centuries later. The Villa Rotunda's venerable squared circle remains, but Palladio's lofty center hall is now an echo expressed in a circular pebble garden, domed by the sky. With the Bath House, Kahn brought Palladio's explorations full circle to the courtyard form of a historically accurate Roman house. The four wings of the Bath House's Greek cross become square pavilions topped by pyramid roofs. The roofs are supported at each corner on a square concrete pad topping an 8-foot square hollow column, open on one side for access.
The hollow columns at the corners of the central circle house U-shaped privacy passages – “baffles,” Kahn called them - leading into the men’s and women’s shower pavilions on each side. These columns house circulation within structure at the corners of the squared circled, just as the Villa Rotunda’s hollowed-out corner masses did in the same arrangement. Kahn’s baffles are even more like Gibbs’ skewed, servant-screening passageways around the central hall of the House for a Gentleman. Kahn repeated this approach at the corners of each of the four pavilions, supporting their roofs with hollow columns containing storage or toilets where they didn’t hold baffles. This recalls the stair- or storage-housing versatility of Colen Campbell’s hollowed corner masses around the rotunda at Mereworth Castle. It also makes each of the Bath House’s square pavilions a Palladian rotunda, supported at the corners by hollow, service-containing structure. The self-contained pyramid roof over each square stands in for the rotunda dome.
Absorbing all of the structural and utilitarian needs of the Bath House, Kahn’s hollow columns leave undisturbed the lofty spaces defined by the open pyramid roofs. Kahn described his priorities in his 1959 Talk at the Conclusion of the Otterlo Congress:
The architect must find a way in which the serving areas of a space can be there, and still not destroy his spaces. He must find a new column, he must find a new way of making those things work, and still not lose his building on a podium. But you cannot think of it as being one problem, and the other things as being another problem.
Actually, these are wonderful revelations because modern space is really not different from Renaissance space.
There’s no indication that Colen Campbell or James Gibbs were conscious influences on Kahn as he designed the Bath House, although his formal education would have exposed him to the mainstream of architectural history in which they figure. It is known that Kahn had Palladio in mind; his personal notebook from the time, on a page marked “Palladian Plan,” records his thoughts on rooms defined by structural bays. He was also known to be fascinated by a particular study of Palladio’s villas in a recent book. The architect and educator William S. Huff was a student of Kahn’s and worked in his office in the 1950s. In a 1981 article, “Sorted Recollections and Lapses in Familiarities,” Huff wrote:
At that time too, an important book came out – Wittkower’s Architectural Principals in the Age of Humanism. Everyone fell over himself to try to grasp it. Palladio was raised to new interest. Palladio meant one thing to Philip [Johnson] - it meant things about proportion and composition. Lou discovered something else in Palladio.
In Palladio, Lou saw the “servant” spaces. He saw that the Villa Rotunda was a great space which he called the “master space” and which was served and surrounded by spaces where the servants were. Kahn saw the analogy with modern times. We no longer have rooms with human servants in them. We now have many spaces with mechanical servants that do the same work that human servants used to do.
So, one of the great principles of Kahn’s architecture, which was formulated about this time, came from his unique way of looking at Palladio.
The Bath House's heavy dependence on plumbing made it a perfect test of Palladio's modern pertinence, which would be proven by Kahn's making it a temple. It follows a long tradition of buildings inspired by the Villa Rotunda and, like earlier examples, carries lessons for others.
Next, we’ll take a further look at Kahn’s interpretation of Palladian principles and explore their application to modern house design.