Seeley Pillar came to Riverside on an excursion train when he was 21 years old. He was a journeyman carpenter from Russell, Ontario, Canada. His skills got him a job soon after his arrival and he became a foreman with contractor John E. Porter, the builder of the Loring Building, the Rubidoux Block, and the Presbyterian Church.
He studied architecture in his leisure hours and began to contract on his own. He earned his architecture license in 1901, and operated both a contracting business and architecture office until, in 1906, the architecture practice had grown enough to give up contracting.
Seeley Pillar designed the Arlington Public Library and Fire Hall, Grace Methodist Episcopal Church, Preston Simons Mortuary, the original Bryant School, the Carnegie Library in Hemet, the Gamble-Estudillo house, and the Speich House. In 1953, Seeley moved to Los Angeles and later returned to the region, settling in San Bernardino.