The Italianate structure known as the U. S. Grant Home was built in 1859–60 as a residence by Alexander J. Jackson of Galena. When Ulysses S. Grant returned to the city in 1865 as a Civil War hero, he was presented the house as part of the city's celebration. All of the rooms are decorated and furnished to represent the mid-1860s. Many of the furnishings belonged to the Grant family.

The site offers exhibits, tours, and occasional recreational and educational events.

The Lewis and Clark site commemorates Camp Dubois, the 1803–1804 winter camp of Meriwether Lewis and William Clark. It was at the camp on Wood River that members of the Corps of Discovery prepared their expedition to the Pacific Ocean. The site's main feature is an interpretive center that contains a large exhibition gallery, a theater, and a gift shop. The 14,000-square-foot exhibition area contains six galleries that outline the background and history of the Lewis and Clark expedition from its conception to its meaning for today's America. A reconstruction of the winter camp is located on the grounds near the visitor center. Its design reflects 1803 U.S. Army regulations for the construction of military posts. A nearby memorial structure overlooks the modern meeting point of the Mississippi and Missouri rivers.

The site offers exhibits, a short film, occasional living history events, and educational and recreational programs.

The Dana-Thomas House, perhaps the best-preserved example of famed architect Frank Lloyd Wright's "Prairie period" dwellings, was built for feminist socialite and heiress Susan Lawrence Dana (1862–1946). Constructed between 1902 and 1904, the house has been restored to appear as it might have been furnished shortly after being built. In 1974 the structure was entered on the National Register of Historic Places and in 1976 was designated a National Historic Landmark. One-hour guided tours begin at the carriage house visitor center, which contains a small exhibit area, an auditorium, and the Sumac Shop. Tours open with a 10-minute orientation video that provides background information on Frank Lloyd Wright, Susan Lawrence Dana, and construction of the Dana-Thomas House. Visitors see a stunning collection of elegant art glass, Arts and Crafts style furniture, dramatic lamps, and ceramics. Several items owned by Susan Lawrence Dana and her family are on display.

The site offers tours, exhibits, a short film, and educational and recreational events.

The O'Fallon Historical Society seeks to preserve and share the history of O'Fallon, Illinois. To this end, the society operates a museum.

The museum offers exhibits.

The Park Forest Historical Society seeks to preserve and share the history of Park Forest, IL. To that end, the society operates a museum and archival center. Park Forest was built as a community for soldiers returning from World War II; and, as such, was the first fully planned suburb to be developed after the war. The museum is located in an original townhouse, and is furnished to a 1948 through 1953 appearance. A portion of the home serves as a re-created school, since townhouses were used as such until permanent educational facilities could be built.

The society offers educational programs, lectures, and outreach speakers. The museum offers guided tours. The archives include circulating oral history transcriptions.

The Old Market House, erected by the city of Galena in 1845–1846, served for 65 years as the city market during the decades of Galena's greatest prosperity as a river port, lead-mining center, and commercial hub. The central section's first floor consists of an entry hall with staircases to the basement and second floor, and a large room providing exhibit and meeting space. The wings hold temporary local history exhibits and provide meeting space for community groups.

The house offers exhibits, tours, and occasional recreational and educational events.

The Frank Lloyd Wright Preservation Trust works to chronicle the life and work of Frank Lloyd Wright, widely regarded as America's most influential architect. The trust maintains Wright's first home and studio, which is located in Oak Park, Illinois, and the Robie House, a masterpiece designed by Wright for his client Frederick Robie.

The trust offers a variety of guided and self guided tours of these landmark buildings. In addition, the trust offers the Wright Plus architectural housewalk, youth architecture workshops, field trip programs, and professional development programs for teachers. The website offers visitor information, a brief biography of Wright, information regarding the two homes maintained by the trust, and information regarding all of the trust's programs.

David Davis (1815–1886) was born in Maryland and studied law in New England. In 1862 President Lincoln appointed Davis to the United States Supreme Court. In 1877 Davis resigned from the court after being elected to the United States Senate by the Illinois legislature and served as Senate president pro tempore from 1881 to 1883. Davis commissioned French-born architect Alfred Piquenard to design this late-Victorian style mansion, primarily as a residence for his wife, Sarah Davis. The three-story yellow brick home comprises 36 rooms. The large, tree-shaded lot includes an 1872 wood house, a barn and stable, privies, a foaling shed, carriage barn, and a flower and ornamental cutting garden. The circular drive to the Mansion remains as originally configured. The property was entered on the National Register of Historic Places in 1972 and in 1975 was declared a National Historic Landmark.

The site offers tours, a short film, and educational and recreational events and programs.

Lincoln's New Salem preserves the site of New Salem village, where young Abraham Lincoln lived for six formative years, from 1831 to 1837. The centerpiece of Lincoln's New Salem is the imaginative recreation of the log village. Built in the 1930s and 1940s as a Civilian Conservation Corps program, the village features twenty-three historically furnished buildings, including several homes, stores, and tradesmen's shops, as well as a tavern, school, wool carding mill, and a saw- and gristmill. Scattered throughout the village are log barns and other outbuildings.

The site offers exhibits, a short film, living history interpreters, performances, lectures, and other recreational and educational events and programs.

The Lemont Area Historical Society seeks to preserve and share the history of Lemont, Illinois. The society's headquarters is in the "Old Stone Church," which served as the home of the Lemont Methodist Episcopal Church between 1861 and 1970. This building also houses a museum, which contains a recreated historical general store, livery stable, school room, and medical office. The society library offers archival materials.

The society offers exhibits, tours of the museum and historic downtown Lemont, and a library. The website offers historic photographs.