The Congregational Church Parish House, completed in 1888, is a striking example of Romanesque Revival architecture designed by Robert W. Hill. The building is characterized by its sturdy masonry, and rounded arches, and the distinctive medieval-inspired tower of the Parish House set a trend in Naugatuck, with many homes in the area following suit by incorporating towers into their designs. A large, arched stained-glass window on the second floor further enhances its architectural appeal, adding a touch of elegance to the structure. John Howard Whittemore was instrumental in commissioning Hill for the design of the Parish House. Whittemore’s vision for the building extended beyond its role as a Sunday School; he wanted it to function as a community center, hosting lectures and other cultural events, in line with his commitment to enriching the town's civic and cultural life.

The Congregational Church of Naugatuck, completed in 1903, was designed by the renowned architectural firm McKim, Mead & White and combines Baroque and Neo-Classical Revival styles. Commissioned by industrialist John Howard Whittemore, the church showcases a harmonious blend of brick and limestone details, with a prominent tower capped by a polygonal spire. Fluted Ionic columns and a broken pediment frame the entrance, while recessed leaded windows line the interior, adding to the church's refined elegance. The church is connected to the Parish House via a portico, creating a unified architectural space.

The building has a stately beauty with a rosy hue and a unique, eye-catching steeple that contributes to its grandeur. The construction of the new Congregational Church came after the old church, built in 1890, was in need of renovation. John Howard Whittemore suggested a new building be constructed, one that would not be located on the Green, allowing for a more open public space. This new building was designed on a grand scale, retaining some of the characteristics of the spired New England meeting house while also seeking inspiration from influential buildings such as Peter Banner's Park Street Church in Boston (1809) and James Gibbs' St. Martin-in-the-Fields in London—two designs that had influenced the construction of many other churches during the period.

Both were designated as part of the Naugatuck Center Historic District on July 30, 1999.