Map of walled cities
The Mishnah on Arakhin 32 lists a number of cities (seen on the map above) that had the unique status of arei homah - walled cities - with the special laws that applied to them. These are defined as cities that were surrounded by walls from the days of Joshua, and they include Zippori, Gush Halav, Yodfat, Hadid, Ono and Yerushalayim.
(This image was taken from the Hebrew edition of the Steinsaltz Talmud, Tractate Arakhin, page 154. To order your copy of the Steinsaltz Talmud, click here (Hebrew site), contact your local Jewish bookstore, or e-mail Koren Books at Bezalel@korenpub.com.)