Terminus was the name originally given to the community which eventually became Atlanta, Georgia. In 1836, the Georgia General Assembly approved the construction of a state railroad to facilitate trade between the Georgia coast and points westward. This area of the Piedmont Plateau was chosen as the terminal for this railroad which was to run, "from some point on the Tennessee River...to a point on the southeastern bank of the Chattahoochee River accessible to branch railroads."
Army Engineer Colonel Stephen Harriman Long was given the duty and the privilege of choosing the best route for this endeavor. After several surveys, Long chose a site eight miles south of the Chattahoochee where "connecting ridges and Indian trails converged." A stake was driven into the red Georgia clay to mark the "terminus", hence the aptly named city. A plaque near Five Points in present downtown Atlanta continues to mark the spot. With an initial city limit of "one mile in all directions", Terminus later became "Marthasville" and in 1847 was finally designated with the name it carries today; Atlanta.
Source: http://www.sos.state.ga.us/tours/html/atlanta_history.html