[3] Its exterior is characterized by deeply folded brick walls created by a series of thin, two-story light hoods that shield windows from direct sunlight.

The church decided to replace it with a building designed "by a leading 20th century architect, giving the community a notable example of contemporary architecture.

"[2] The search committee, formed of church members who were knowledgeable about architecture, decided to focus on prominent architects who had established relatively small offices and did most of the creative work themselves.

[7]: 52  They spent a day with Louis Kahn in May 1959[9]: 138  and were impressed by his philosophical approach, the atmosphere in his office, the assurance that he would personally be in charge of the design, his respect for the integrity of materials, and the perception that his architecture, while modern, had an emotional depth and a connection to the past.

He worked as assistant architect on the Jersey Homesteads, a project to resettle Jewish garment workers from New York City and Philadelphia to a kibbutz-like rural collective that combined farming and manufacturing.

[9]: 39 Kahn gave a philosophical presentation of his ideas to a congregational meeting in June 1959, after which the church commissioned him to design their new building.

"[5]: 64 When Kahn addressed the congregational meeting that voted to hire him, he explained his approach by creating what he called a Form drawing, which, he said, was not to be understood as an architectural design.

"[5]: 110  Kahn had developed the idea for this type of ambulatory prior to his work on First Unitarian, referring to it during a talk in 1957 in the context of a university chapel.

[9]: 142 The central room was to be capped by a complex dome and encircled by a corridor outside its walls that would provide connections to the three-story church school on the periphery of the building.

[10]: 342 Kahn agreed to create a new design, much to the relief of the building committee, who feared that he would demand payment for work performed and walk away from the commission.

He resisted suggestions to place classrooms in a separate wing to reduce the potential for services to be disturbed by boisterous children, retaining the concept of surrounding the sanctuary with the church school.

[10]: 343  One option would have been to span the sanctuary with a steel frame, but Kahn had decided in the early 1950s that he would no longer use such structures, preferring the more monumental appearance he could achieve with materials like concrete and brick.

One member built a scale model of the building and used it to conduct photometric studies of light levels in the proposed sanctuary.

[10]: 343  The committee notified Kahn that their calculations of acoustical resonance in the proposed light shafts indicated the possibility of problems in that area.

[10]: 343  Komendant said, "He told me that in his speech he described the cathedrals, whose size and height was intended to show God's greatness and might and man's lowness, so that men would be frightened and obey His laws.

"[16]: 40 The exterior of the building is characterized by deeply folded brick walls created by a series of thin, two-story light hoods that help shield windows from direct sunlight.

[21]: 274  The light hoods create a series of shadows on the exterior wall that are reminiscent of a row of columns, their vertical lines adding to the impression of height.

[11]: 176  The windows of these rooms are recessed so deeply as to be unnoticed when viewed from an angle, and the building's indented corners spaces are windowless, all of which adds to the perception that the sanctuary is surrounded by massive, rugged walls.

The ceiling's layered outer edges and light-filled corners give the room "an expansive, boundless character", according to Kahn biographer Robert McCarter.

Its outer edges do not sit directly on the sanctuary walls but rise above them, relieving what could be a perception of oppressive weightiness, according to Carter Wiseman, one of Kahn's biographers.

[9]: 159  As he had done earlier with the main stairwell in the Yale University Art Gallery, Kahn also left visible the pattern of circular holes created by the devices that held the forms together while concrete was being poured for the walls, letting the marks of construction serve as the "basis for ornament".

"[9]: 203  Because his social agenda was compatible with Unitarian ideals, he was in a good position to manifest his vision of community in architectural form at the Rochester church.

[9]: 207 Kahn's first major essay as sole author, published in 1944, was called "Monumentality," a concept he defined as "a spiritual quality inherent in a structure which conveys the feeling of its eternity".

An overriding concern for him from this period on was to instill a sense of permanence into his buildings, so that his work could match the dignity and poise of the ruins he had seen in Italy and southern Europe.

[9]: 208  At First Unitarian, says Goldhagen, the column-like rhythms of light that Kahn sculpted across the facade are among the devices that increase the impression of massiveness and give the building an air of monumentality.

This requires acute perception of one's social and physical environment, which is difficult because a person tends to apprehend the objects and buildings that surround her as instruments".

"[9]: 61  In contrast to other modern architects like Mies van der Rohe, Kahn shunned "the diaphanous and the transparent so that he could press the viewer up against materiality, substance and weight.

"[9]: 212  Kahn strove for an aesthetic of authenticity at First Unitarian, says Goldhagen, by designing with a blunt honesty of materials and by laying bare the process of construction.

The Yale University Art Gallery, for example, with its emphasis on process over finish, promotes authenticity, situating people in themselves, while the Richards Medical Research Laboratories were designed to reinforce group cooperation.

Goldhagen says that it was with First Unitarian that Kahn first succeeded in situating his building's users both in themselves and in society, an agenda that he was later able to develop more fully at the Salk Institute and National Assembly Complex in Dhaka, Bangladesh, which had much larger budgets.