本研究分析了西漢和唐朝的首都長安高牆外的地區。針對兩朝城牆內城市化地區所做的史學與考古學研究成果雖然已經非常豐碩，然而周邊地區卻尚未受到充分系統化的探討。透過使用自二十世紀初葉開始以一比一萬比例所做的精細測量地圖調查，結合保存下來的地理史料和建築計畫書，一個地理資訊系統(GIS)於焉誕生。這個系統指出貫通城外與城內，並將門道與大街連為一體的棋盤式道路構造。藉由比對兩個朝代的地標可以發現，這種道路網絡至少在西漢時期便已經存在，唐代長安城的新城市設計則是繼承了這個棋盤式的街道布局，而該城又確實有一些在傳統重建上存在的區塊，可能實際上是沒有如此動工過的。這件GIS很快便會開放提供給大眾使用。

This study analyzes the area outside the city walls of the Western Han and Tang imperial capitals of Chang'an. Although there has been considerable historical and archaeological research on the urbanized area within the walls of these two cities, the surrounding areas have not previously been systematically investigated. Through the use of detailed survey maps at a scale of 1:10,000 from the early twentieth century, coordinated with archaeologically documented remains and reconstructed plans of the cities themselves, a Geographical Information System (GIS) has been developed. This GIS graphically indicates the remains of a grid of roadways outside the city walls, relating to gateways and major avenues within the cities. The coordination with landmarks from these time periods shows that there was a planned network of roads in this area at least as early as the Western Han, that the Tang city of Chang'an was planned in conjunction with this grid of roadways, and that there are certain areas of of the Tang city where the regular grid of streets and neighborhoods may not have actually been built as shown on the traditional reconstructions. The GIS will be available on line for public access.