Nine-Mile Circle

The Nine-Mile Circle was a streetcar line of the Atlanta Street Railway, later the Atlanta Consolidated Street Railway which went from downtown Atlanta to today's Virginia-Highland neighborhood as follows:

from Marietta and Broad to Peachtree Street and north along Peachtree
east on what was then Houston St.
north along N. Boulevard to
Ponce de Leon Ave. from where it made a loop:
*north along N. Boulevard
*east on Virginia Ave.
*south along N. Highland Ave., and
*west on Ponce de Leon back to the intersection of Ponce de Leon and Boulevard.

The line started operation in late 1889, and was the second electric line in Atlanta, after the Edgewood line to Inman Park.
The line was an extension of an earlier horsecar line:

The original line went from downtown Atlanta up Peachtree to Pine
Extended in August 1872 to "Ponce de Leon Circle".
At some point later it was extended to Ponce de [Leon Springs (Atlanta)|Ponce de Leon Springs], where the Ponce de Leon amusement park would be built; today, Ponce City Market stands on the site.
Finally in 1889 the line was electrified and extended with the "loop" around what is now Virginia-Highland.

In its heyday in the 1890s, the Nine-Mile Circle line was one of the streetcar lines popular for pleasure trips. It also took visitors to the Cotton States and International Exposition in 1895, held in what is today Piedmont Park.
At some point, service in a loop was discontinued. Service to the area did continue as individual lines however:

Along North Boulevard as far as Orme Circle
Along Ponce de Leon Ave. from downtown past Druid Hills out to Decatur, and
Along North Highland Ave. as far north as Virginia Ave.