The twenty-six-acre campus of Concord Academy, an independent, coeducational secondary school for boarding and day students incorporated in 1922, lines the north side of lower Main Street. A row of eight massive multistory clapboard houses (c. 1780–1830) serves as dormitories and administrative offices. Behind them, a complex of academic buildings, including a fine nineteenth-century frame meeting house moved to the site, extends to the Sudbury River. Two additional properties—228 Main Street (c. 1894) and 185 Main Street (c. 1805–1810)—house the headmaster and faculty.
The Main Street row records Concord's emergence as a wealthy town, driven by the presence of the courts. At 122 Main Street, Wheelock/Shepherd's Tavern (c. 1794–1796) was a prominent meeting place. A wing became 128 Main Street (c. 1829–1839); overflow boarders rested at the Georgian-style 140 Main Street (c. 1780). Steady prosperity financed fashionable renovations: in 1819, to 158 Main Street (c. 1810) by prominent lawyer Samuel Hoar; in 1838, to 186 Main Street (c. 1813) by manufacturer David Loring, who added the monumental Doric columns. In 1845, Ebenezer Rockwood Hoar, Samuel's son, built the Greek Revival mansion at 194 Main Street. The huge brick-ended double house at 204–206 Main Street (c. 1820) was likely a rental investment.
Adaptation to this historic, accessible setting came naturally to Concord Academy, whose philosophy stresses intellectual development balanced by a sense of simplicity, responsibility, and contribution to the larger
Located around a central green, renovated classroom buildings and the Math and Arts Center (1994) give a nod to Federal details: in repeated patterns of six-over-six framed windows, in roofs of similar pitch, in dormers, in connecting breezeways and ells, and in uniform use of clapboard siding. The placement and scale of windows, in particular, help integrate the brick facades of the Student, Health, and Athletic Center (1998, Graham Gund Architects) with the campus.
On the opposite side of Main Street stands an equally distinguished group of houses. At 255 Main Street, the Thoreau-Alcott House (c. 1820, NR), a clap-boarded three-bay structure with projecting pedimented porch, incorporates Henry David Thoreau's 1849 south wing with shed for a pencil factory and an 1877 west wing added for the Alcott family. At 325 Main, the Jones/Channing House (c. 1767) is the earliest dwelling on the street and a classic example of late Georgian architecture. Two exceptionally fine residences dating from 1845 stand next to each other at 300 and 310 Main Street, both impressive examples of the Greek Revival style.