Reference for Arakhin 9:6
עִיר שֶׁגַּגּוֹתֶיהָ חוֹמָתָהּ, וְשֶׁאֵינָהּ מֻקֶּפֶת חוֹמָה מִימוֹת יְהוֹשֻׁעַ בִּן נוּן, אֵינָהּ כְּבָתֵּי עָרֵי חוֹמָה. וְאֵלּוּ הֵן בָּתֵּי עָרֵי חוֹמָה, שָׁלשׁ חֲצֵרוֹת שֶׁל שְׁנֵי שְׁנֵי בָתִּים, מֻקָּפוֹת חוֹמָה מִימוֹת יְהוֹשֻׁעַ בִּן נוּן, כְּגוֹן קַצְּרָה הַיְשָׁנָה שֶׁל צִפּוֹרִים, וְחַקְרָה שֶׁל גּוּשׁ חָלָב, וְיוֹדְפַת הַיְשָׁנָה, וְגַמְלָא, וּגְדוֹד, וְחָדִיד, וְאוֹנוֹ, וִירוּשָׁלַיִם, וְכֵן כַּיּוֹצֵא בָהֶן:
A city whose roofs [look as if] they form its wall, or one that was not encompassed by a wall in the days of Joshua ben Nun, is not considered like houses in a walled city. [A house in any of] the following counts a house in a walled city: [those in a city] of no less than three courtyards, having two houses each, which have been encompassed by a wall in the days of Yehoshua bin Nun, such as the old stronghold of Tzippori, the fort of Gush-Halav, old Yodfat, Gamla, G’dod, Hadid, Ono, Jerusalem and other similar cities.