 He moved to Pittsburgh from Germany in 1880, established a Pittsburgh office in 1884, established the Aspinwall-Delafield Land Company in 1904, and built about a dozen Catholic churches in the area.Perhaps his most notable works are St. Stanislaus Kostka Church (1891) in the Strip District of Pittsburgh, (1896) on Mount Washington in Pittsburgh, in Homestead (1895), (1898) in East Allegheny on the North Side of Pittsburgh, the old St. Nicholas Croatian Catholic Church (1900) in Troy Hill, and the St. Nicholas Croatian Church in Millvale (1922).In 1898, Sauer built a home for himself in Aspinwall, Pennsylvania.