The Topsham Historic District is comprised of fifty-eight buildings that represent architectural styles spanning roughly 150 years from early nineteenth century to the mid-twentieth century. Collectively, the majority of the district consists of buildings designed in the Federal or Greek Revival styles. Nineteen of these dwellings were constructed prior to 1820. All of the houses and buildings sit in close proximity on seven streets and exhibit traditional architectural characteristics of symmetrical design typical for the time period.

New Gloucester's significance is evident in this historic district. It was one of the few well-established inland Maine communities during the late eighteenth century. The large variety of Federal-style two-story dwellings demonstrates the town's early prosperity, found mostly through agricultural pursuits. Thirty-one properties are listed in this district and twenty of them pre-date 1820. The land that became New Gloucester was granted to sixty citizens from Gloucester, Massachusetts, in 1735.

Although construction of the Kate Douglas Wiggin House began in 1797, it was not completed until the early 1800s. Jabez Bradbury started the house, but it was completed by neighbor Thomas Carll after the two men decided to swap houses. The house was purchased by the distinguished educator and author, Kate Douglas Wiggin, in 1905. She and her sister named the house "Quillcote", meaning home of the pen. Born in Philadelphia, her family moved to Maine at an early age.

Located northwest of the town center, the Sam Perley Farm contains a good example of a Federal-style farmhouse. Two stories high, the house is sheathed in clapboards and topped by a side-gabled roof. The facade is symmetrical with a central entry located in a projecting vestibule. The entry door is flanked by sidelight windows and topped by a louvered fanlight. The gabled dormers were likely added later. A large chimney sits in the center of the roof. The farm also includes a carriage house, wellhouse, and barn.

The Lt. John Hathorn House is a well-preserved early Federal period house in the Mid Coast region. It's located in a rural area in northern Woolwich. The dwelling is two stories tall, with clapboard siding, a side-gabled roof and a large center chimney. The symmetrical facade contains a central entry door that is framed by wood pilasters supporting an entablature and projecting cornice. The upper story windows are placed just below the roof eaves. The interior features fine wood paneling.

Likely constructed to house two families, the Lithgow House is unusual for its dual entrances behind an enclosed vestibule. Two stories tall, the house is clapboard sided with a side-gabled roof and two interior chimneys. The facade is slightly unsymmetrical, reflecting the atypical floor plan inside. The projecting vestibule leads to two entry doors which are placed at forty-five degree angles, each of which open to a parlor. A central staircase can be accessed from either room, leading up to the second floor which contains four chambers of various sizes.

Located on a road that historically led inland from Kittery, the Dennett Garrison is one of the earliest surviving buildings in the state. Constructed using the post-and-beam system, the two-story house is a large rectangle with a steeply pitched side-gabled roof. It is sheathed in clapboards and has a large center chimney. The facade is symmetrical with a center entry door. The interior walls are hand-hewn hemlock on the first floor and oak on the upper floors. John Dennett purchased the property in 1698.

The John Perkins House, located on Perkins Street, is an example of Georgian-style architecture. The house is clad in clapboard siding and has a symmetrical front facade. The front facade's most notable feature is its entry: a paneled front door with sidelights, Doric pilasters, cornice, and a prominent triangular pediment. The framing timbers are hand-hewn and mortised and tenoned with pegs or treenails. John and Phebe Perkins were one of the first families to build a house in Castine.

The Weston Homestead is a large two-story wood-frame building with a side-gabled roof, set on the east bank of and facing the Kennebec River. Clapboard sided with a symmetrical facade and two large interior brick chimneys, the homestead is a well-preserved example of rural Federal-style architecture. The centered entry door is flanked by Doric pilasters and topped by a fanlight and lintel with dentil molding. A two-story ell extends to the rear to connect to the carriage barn. The house was built by Benjamin Weston, whose father settled in the Canaan area in 1771.

The Laura Richards House is a good example of Federal period architecture in the Gardiner area. It is a two-story clapboard sided structure with a hipped roof. The facade is symmetrical with a central entry door framed by sidelights, fanlight, and simple wood pilasters that support a wide entablature. The cornice is denticulated and a shed dormer sits in the center of the roof. Ebenezer Byram built the house after purchasing the land from Robert Hallowell Gardiner. The house's most significant resident was Laura Richards, a renowned author, who lived here from 1878 until her death in 1943.