[1] The city of Marlborough is located in far western Middlesex County, Massachusetts, in the outer ring of Greater Boston fringed by Interstate 495.

This portion of Main Street was once designated as U.S. Highway Route 20, which now runs along a bypass just south of downtown.

[2] Most of the commercial buildings in the district are made of brick and stone, and were built in the late 19th or early 20th century.

City Hall is a well-kept Beaux-Arts building designed by Allen, Collens & Berry, and built in 1905.

There are four churches, and several stylish Queen Anne Victorian houses, notably that of Judge James MacDonald at 23 Prospect Street.