The success of the Boston Manufacturing Company Mills led to the development of a
Beyond the town common commercial core, major institutions chose Main Street as it extended to the west. Churches marked the importance of the mill economy when the Trinitarian Congregationalists separated from the Unitarian Church of Christ and constructed a new church (730 Main Street, NR) in 1870, a clap-boarded structure (now encased in aluminum siding) with staged tower and steeple that retained the image of a colonial meetinghouse. The expanding Episcopal parish built the dramatic Christ Church (750 Main Street, NR) in 1898, using field-stones from the Waltham estate of philanthropist Robert Treat Paine to carry out the nubby design by Peabody and Stearns. Across Main Street, Loring and Leland provided a handsome design in Federal Revival brick for the Waltham Public Library (1915, 1994 expanded, Shepley, Bulfinch, Richardson and Abbott, 735 Main Street, NR). In 1935–1936, Boston architects Wadsworth, Hubbard and Smith designed the U.S. Post Office (774 Main Street, NR), a two-story brick Colonial Revival building and a typical product of the Public Works Administration.