The largely residential district around Winthrop Square features some of Charlestown's earliest surviving frame and brick residences and one of the oldest surviving public grammar schools in the Boston area. The park is a remnant of the original training ground used by the local militia in the colonial period. Relandscaped several times in the nineteenth and early twentieth centuries, the present configuration of three entrances with paths, benches, and iron fences dates to 1919. The 1872 Soldiers' and Sailors' Civil War Monument, designed by Martin Milmore, replaced an earlier three-tier cast-iron fountain.
The Old Trainingfield School (5 Common Street) was built in 1827 as a primary school. The main entrance was originally through the recessed arch on the gable end. One of several schools located on the Trainingfield, it was moved to its present site in 1847 or 1848. The frame two- and three-story houses around the square are well-preserved examples of the type of housing constructed in port towns for a community's middling sort in the Federal period. Known locally as the Salem Turnpike Hotel, 16 Common Street/19 Putnam Street, a five-bay, two-and-a-half-story hipped roof earlier structure with a two-bay, two-story extension, are two of the four oldest houses
The row of thirteen attached town houses on Adams Street, all built in the antebellum period, include some of the town's earlier brick row housing, several of which were constructed on speculation for middle-class families by local building craftsmen. The oldest are 9–12 Adams Street, completed by 1830. Each originally stood three stories under a side gable roof with a side-hall plan, an integral service ell, and Greek ornament.