能夠實地測繪長安城圖，全面而實時的做到古今對照，是唐代研究者的普遍心願。為此，本文採用數位方法，繪製唐長安城圖，命名為〈唐長安城數位新圖〉，從底圖的選定、數據的計量，到城線、坊里線、等高線、河川線，圖中的一切都在Google Earth Pro衛星地圖上繪製。使用者可以一鍵按下去，古今沒有距離，所見唐城即是今城。本文除了紙本論文之外，也製作了GIS互動平台，與論文的內容同步上網，名為《天下通衢－中國歷代水陸路程》第三部。本文有三大優勢，第一，收納北宋迄今的唐長安城圖，以及清末至民國間的西安老地圖，全部予以數位化並上網，讀者可以利用。第二，詳細解說〈唐長安城數位新圖〉的繪製過程，使讀者知所由來。第三，以唐人詩例指出如何活用〈唐長安城數位新圖〉，開創唐詩研究的新途徑。

It is a widespread aspiration of Tang Dynasty researchers to conduct on-site surveys and create a comprehensive and real-time comparative map of Chang'an city across different eras. To achieve this goal, this paper employs digital methods to draw a map of Tang Chang'an city, and name it New Digital Map of Tang Chang'an City. All things in this map, from the selection of the base map and data measurement, to the delineation of city walls, streets, contour lines, and river courses, are drawn on Google Earth Pro satellite map. Users can transcend time and space to view the Tang city from where it stands today simply by clicking one finger. In addition to the printed paper, the authors also create an interactive GIS platform, which is uploaded together with the content of this paper, and is entitled as Thoroughfares under the Heaven: The Complete Maps of Water and Land Routes Throughout the Dynasties of China, Part Three. This paper boasts three major advantages. Firstly, it digitizes and makes all Tang Chang'an city maps from the Northern Song Dynasty up to the present, as well as old maps of Xi'an from the late Qing Dynasty to the Republic of China era, accessible to readers. Secondly, it provides a detailed explanation of the process of creating the New Digital Map of Tang Chang'an City, giving readers insight into its origins. Lastly, it uses examples from Tang Dynasty poetry to demonstrate how to use the New Digital Map of Tang Chang'an City effectively, in order to pave the way for new approaches in Tang poetry research.