Watertown Square was the site of the industrial core for colonial Watertown (granted 1630) and the limit of navigation on the Charles River. Where the religious and political core developed around 1760 farther east at
Main Street, heading west from Watertown Square, contains one of the finest groups of bank buildings in the Boston area. The earliest of three banks is the Watertown Savings Bank (1892, Charles Bridgman, 56 Main Street), built of yellow brick with limestone trim and evoking the private club–like nature of banking at this time. The structure originally extended farther to the west, but that half was replaced by a monumental limestone addition (1928, R. Clipston Sturgis, 60–68 Main Street). A similar scale and classical character is seen in the former home of the Union Market National Bank (1920, Dennison and Hirons, 1 Galen Street), a commercial bank chartered in 1873 to accommodate the expanding business of the nearby Union Market, where cattle were unloaded for the slaughterhouses in Brighton. Constructed of limestone, the two-story bank, lighted by monumental arched windows and doorway, anchors the transition from Watertown Square into Main Street.
At the western end of the Watertown Square district stand two fine examples of civic architecture. The Watertown Free Public Library was founded in 1869 and moved in 1884 to this building at 123 Main Street, a red brick and brownstone structure designed by Shaw and Hunnewell (with a 1956 red brick and brownstone addition with a flat-roofed lower modernist scale by Campbell and Aldrich). The western climax of this Main Street civic group is Town Hall (1932, R. Clipston Sturgis, 149 Main Street), a substantial Colonial Revival design in red brick, ornamented with busts of Washington and Lincoln in niches, a pedimented composite portico, and a slender cupola.