Dover was founded as the court town for newly established Kent County in 1683 by William Penn, the proprietor of the territory generally known as the "Lower Counties on the Delaware." Later, in 1717, the city was officially laid out by a special commission of the Delaware General Assembly. The capital of the state of Delaware was moved here from New Castle in 1777 because of its central location and relative safety from British raiders on the Delaware River. Because of an act passed in October 1779, the assembly elected to meet at any place in the state they saw fit, meeting successively in Wilmington, Lewes, Dover, New Castle, and Lewes again, until it finally settled down permanently in Dover in October 1781. The city's central square, known as The Green, was the location of many rallies, troop reviews, and other patriotic events. To this day, The Green remains the heart of Dover's historic district and is the location of the Delaware Supreme Court and the Kent County Courthouse.
Dover was most famously the home of Caesar Rodney, the popular wartime leader of Delaware during the American Revolution. He is known to have been buried outside Dover, but the precise location of his grave is unknown. A cenotaph in his honor is erected in the cemetery of the Christ Episcopal Church near The Green in Dover.
Dover and Kent County were deeply divided over the issue of slavery, and the city was a "stop" on the Underground Railroad because of its proximity to slave-holding Maryland and free Pennsylvania and New Jersey. It was also home to a large Quaker community that encouraged a sustained emancipation effort in the early 19th century. There were very few slaves in the area, but the institution was supported, if not practiced, by a small majority, who saw to its continuation.
The Bradford-Loockerman House, Building 1301, Dover Air Force Base, John Bullen House, Carey Farm Site, Christ Church, Delaware State Museum Buildings, John Dickinson House, Dover Green Historic District, Eden Hill, Delaware Governor's Mansion, Greenwold, Hughes-Willis Site, Loockerman Hall, Macomb Farm, Mifflin-Marim Agricultural Complex, Old Statehouse, Palmer Home, Town Point, Tyn Head Court, and Victorian Dover Historic District are listed on the National Register of Historic Places.