George Rogers Clark National Historical Park is located in Vincennes, Indiana, not Illinois.

The park commemorates the achievements of George Rogers Clark, an American Revolutionary War hero who led the capture of British-held Fort Sackville in 1779, which secured the northwest territory for the United States. It was established in 1936 and includes a visitor center, memorial, and replica of Fort Sackville.

One of the main reasons to visit the park is to learn about the history of the American Revolution and the critical role that George Rogers Clark played in securing American independence. Visitors can explore the visitor center's museum exhibits, which include artifacts and interactive displays. The memorial features a statue of Clark, and the replica of Fort Sackville offers a glimpse into what life was like during the Revolutionary War.

Other points of interest at the park include the Lincoln Memorial Bridge, which spans the Wabash River and provides scenic views of the area. The park also hosts events throughout the year, including reenactments and living history demonstrations.

Interesting facts about the park include that it is the oldest national historical park in the western United States and was once home to a bustling trading post. Visitors can also see a piece of the original Fort Sackville's flagpole, which was used to raise the American flag after the fort's capture.

The best time of year to visit the park is during the spring or fall when temperatures are moderate and the foliage is colorful. However, the park is open year-round and offers opportunities for hiking, picnicking, and other outdoor activities.