The Windham Textile & History Museum (also known as the Mill Museum of Connecticut) was founded in 1989 in Willimantic, a former industrial borough located in the Town of Windham in Windham County, CT. At that time, the Museum acquired ownership of two buildings that had been part of a factory complex once owned by the American Thread Company. ATCO had shut down its Willimantic plant in 1985 and moved out of state. The new owner of the plant, a real estate developer named Jonathan Dugan, had subsequently transferred two of the smaller buildings to the Museum as a gift. Both buildings were located on the north side of Main Street, across the street from the rest of the plant, on a triangular lot bounded by Main Street on the south, Union Street on the northeast, and two privately owned parcels (one containing a Main Street commercial building, the other a Union Street dwelling) on the west. A small, paved parking lot lay between the two buildings, and was part of Dugan’s gift. Both buildings were constructed into the side of Carey Hill, so that the first floor of each opened at ground level onto Main Street and the second floor of each opened at ground level onto Union Street.

The larger of the two buildings, known as Dunham Hall, was a three-story structure without a basement, mostly constructed in 1877. Originally, the first two floors of this structure had been the company store for the Willimantic Linen Company, the predecessor of the American Thread Company. The third floor had been a library for the WLC’s workers, their families, and other members of the community. Built in Queen Anne / Stick-Eastlake style, Dunham Hall originally featured stick style exterior crossbeams, a sweeping sloped roof with dormers, decorative chimneys, and other attractive High Victorian / Gilded Age features. The exterior of the first floor was brick, the exteriors of the second and third floors were wood. Despite the presence of fireplaces on the third floor, the building was heated by steam. In the early 1890s, the WLC closed the company store.

When ATCO purchased the entire plant from the WLC in 1898, it converted the lower two floors of Dunham Hall into its principle office building. It new bathrooms and interior partitions. It altered the fenestration on the north side, along with a concrete-lined trench, possibly to discourage ground water from entering the building. It removed the original grand staircase, floored over the opening, and replaced it with a smaller staircase in a different location. It reconstructed some of the entrances.

The floor on the first level was poured concrete covered with linoleum, which at some point was replaced with tiles. The floor on the second level was composed of several different types of wood boards: maple, oak, and softwood. Portions of this floor, too, were at some point covered with tiles. ATCO resided the exterior of the upper two floors with wood shingles, removing most of the stick-style crossbeams. Several times, ATCO changed the color of the exterior paint on the wooden portions of the building, which has variously been brown, green, and beige.

The third floor remained a library until about 1940, when it was converted into meeting rooms – at which time, all of the built-in oak and cypress bookshelves were removed.

ATCO did retain some nineteenth-century features, however. These included decorative woodwork with trefoils on all three floors, Eastlake-style ceiling beams on the third floor, wainscoting on the third floor, and fireplaces on the third floor. Much of the building had changed, though. Therefore, historically, Dunham Hall had not one but three different incarnations as a historical structure, used first as a company store and library 1877-1898, then as office space and library 1898-40, and finally as office and meeting space 1940-1985. Each change brought extensive renovations. The Museum has records of many of the renovations in the form of architectural plans and blueprints left behind by ATCO when it moved in 1985.

The second building, known today as Dugan Mill after Jonathan Dugan, was originally a one-story-and-basement brick structure erected by the WLC in 1877 as a warehouse. In the first decade of the twentieth century, ATCO added a brick second floor, designed as the headquarters of the Company’s American Fire Brigade. In the 1920s, ATCO disbanded the fire brigade and completely remodeled the second floor (accessible only from Union Street) as a meeting hall, with adjunct kitchen, coatroom, and toilet. The floor remained maple hardwood, although at some point ATCO covered the wood with tiles. Also at some point, ATCO converted both floors into office space for its engineering department. Thus the Dugan Mill building, like Dunham Hall, had not one but several different historical incarnations as a structure, used at different times as a warehouse, fire brigade headquarters, meeting hall, and office space. Each change of use was accompanied by extensive renovations. Many of these renovations are recorded on blueprints and architectural diagrams left by ATCO when it moved in 1985.

When the Museum acquired these buildings, it made further, extensive renovations. In most cases, these renovations altered the original uses of the spaces to more traditional museum uses. Only three spaces remained mostly unaltered by the Museum in 1989: the second floor of the Dugan Mill (which the Museum has restored to its 1920s appearance as a meeting room, although with the addition of modern ADA-compliant restrooms), the library reading room on the third floor of Dunham Hall, and the basement of the Dugan Mill building. (Because of water seepage from Carey Hill, the basement of the Dugan Mill building is usable only as a furnace room and very rough storage.)

In the late 1990s, for financial reasons, the ownership of both buildings and the grounds were transferred to the Town of Windham.