In 1855, Colonel John Harris and his wife Henrietta built a two-story, all brick, Greek revival house "on a ridge just east of town." The home was known as the "Mansion House." Today, it houses the Society's headquarters and serves as a visitor center and house museum.

The society offers tours, educational programs, research library access, and occasional recreational and educational events; the house offers tours.

The Society's Museum is located in a structure dating back to 1823. The building was part of a 10-acre estate with carriage house, tool shed, vineyard, garden, and orchard. The Mynderse Family lived there until 1875 when Mrs. Leroy Partridge purchased the house and began an extensive remodeling and updating that changed the two story dwelling into the three-story, 23-room, Queen Anne style home that stands today. The original Gothic Revival tool shed is now the "Bee Hive," a replica of a general store , located behind the house. Also located in the back yard is the Town Clock that was once on top of the Hoskins Block and moved to the grounds by Texaco Oil in October 1968. The first floor of the Museum shows a combination of the original furnishings of the house as the Partridge and Becker families lived here, as well as reproductions and decorations both complimentary to the time period and from historical events in Seneca Falls.

The society offers occasional recreational and educational events; the museum offers exhibits and research library access.

The Society operates the historic Kiersted House as its headquarters and museum. The Kiersted House is architecturally significant as an example of early-18th and 19th-century local building craft and practices. The original builder is still unknown, but the first recorded owner of the homestead was Hiskia Dubois in 1724, and it was purchased by Dr. Christopher Kiersted in 1773. The House displays changing exhibits on local history.

The society offers occasional recreational and educational events (including living history events); the museum offers exhibits.

The Society operates the 1860 Port Washington Historical Society Light Station Museum.

The society offers research library access; the museum offers exhibits and tours.

Historic Ritzville maintains two museums. The Burroughs Home was the residence of Ritzville's pioneer physician, Dr. Frank R. Burroughs. It has been restored to its original condition and its collection highlights clothing and household items from the 1890s to the 1920s. The Depot features commercial artifacts relevant to Ritzville around the turn of the century. These include the town's original horse-drawn hearse and a working telegraph machine.

In 1938, the Society assumed the management of the 1936 Hall of State at the request of the City of Dallas. The Hall of State is one of the finest examples of art deco architecture in the country and is listed on the National Register of Historic Places as a part of Fair Park.

The society offers tours, educational programs, lectures, research library access, and occasional recreational and educational events; the hall offers exhibits and tours.

The Society, founded in 1897 to inform the world of the achievements of the Irish in America, is today a national center of scholarship and culture. From its home on New York's Fifth Avenue, the Society serves as a focal point of the contemporary transatlantic Irish experience, a place where current public issues are explored, and where the great renaissance in Irish culture is celebrated in lectures, concerts, art exhibits, and a literary journal.

Does not appear to be affiliated with any specific historical sites.

The Society maintains three historical properties, including the Beall-Dawson House, the Stonestreet Museum of 19th-century Medicine, and the Waters House History Center. Visitors can learn about the county's beginnings at the historic 1815 Beall-Dawson House, an elegant federal style townhome that features period rooms and changing exhibits. The museum tour highlights the culture and daily life of both the upper-class Beall family as well as the enslaved African Americans who labored in the house and on the adjacent property. The Stonestreet Museum offers an insider's look into the developments in medical science that occurred during the career of Dr. Edward E. Stonestreet. Built in 1852, this unique one-room Gothic Revival doctor's office features medical artifacts and implements that demonstrate the fascinating changes that occurred in the 19th and early 20th centuries. The Waters House History Center is housed in oldest house in Germantown—built in three parts, the oldest dates to the mid-1790s. It offers exhibits related to local history.

The Society offers educational programs and lectures; the Beall-Dawson House offers exhibits, tours, and occasional educational and recreation events and programs; the Stonestreet Museum offers exhibits and tours; the Center offers exhibits and occasional recreational and educational programs.

The Society collects and preserve books and pamphlets, maps, manuscripts, photographs, newspapers, and periodicals pertaining to the history of Westchester County; promotes the knowledge and understanding of that history; and advocates for the preservation of the county's architectural heritage.

The society offers research library resource, educational materials, and occasional recreational and educational events.

The Society operates a museum which offers exhibits on local history.

The society and museum offer exhibits, tours, educational programs, lectures, and occasional recreational and educational events.