Built in 1848, it is a fine example of institutional Greek Revival architecture, and is one of the city's older surviving school buildings, built during the rapid population growth that followed the city's industrialization.

It is a large two story brick structure, rectangular in footprint, with a gable roof with the end facing the street.

The buildings main entrances were historically on the north and south facades; they are sheltered by late 19th-century porticos, and the northern one is now the primary access.

The Colburn School was built in 1848, named for Warren Colburn, a superintendent of the Merrimack Manufacturing Company, and originally provided single classrooms for grades 1-3 on the ground floor, and 4-8 on the upper floor.

In 1863 it was converted to a fully graded school, and its interior was reconfigured to house eight classrooms.