西安與羅馬各自擁有豐厚的歷史積澱與城市遺址，其在保護與發展之間的張力、互動值得比較。西安歷代都城曾屢次短距離「水平遷移」，留下多處大型遺址區；羅馬城則始終定著於一處，後代城市層層「垂直疊壓」於舊城之上。兩座古都基於其興衰歷程、以及重要的文化象徵地位，如今皆以保護遺址、發展旅遊作為重返輝煌的手段。大型城市遺址既延遲城市現代化的進程，同時亦是全球地域化下城市發展的獨特資源。結合文獻與實地調查，本文以分析兩類遺址的歷史成因、耙梳兩種保護思維的轉變為基礎，探討遺址分佈的特殊性如何分別引導西安、羅馬城市風貌的形塑，細察遺址保護與城市發展之間的互動。本文指出兩種「將時間空間化」的方式：西安著重「空間脈絡」的完整性，催生各朝代空闊遺址及其背襯的仿古高樓天際線，移植古風的城市新區遂於地圖中浮現；羅馬則力圖呈現「時間脈絡」，層疊積累的各年代遺構錯綜拼貼於不同深度的城市地底，依序凝凍於地層剖面中。本文同時剖析、反思推動此種互動關係的社會、政治與經濟力量。

This research aims at comparing how the horizontally distributed historic heritage sites and vertically layered ones influence contemporary urban development, conservation practice, and the creation of cityscape. This article explores how such paired spatial configuration, either horizontality or verticality, shapes historic urban landscape. Xi'an and Rome are chosen to make this comparison. Xi'an is a city with several ancient heritage conservation areas scattering horizontally while Rome's urban relics are layered vertically throughout history. Similar experiences of rise and fall left the two cities with rich ancient relics that were obstructions to modernization but nonetheless monopoly resources for development. Longing eagerly for revival, both of them coincidentally adopt the same strategy of capitalizing on the cities' splendid past to nurture cultural tourism. Based on archives, maps, planning documents, and on-site empirical research, this article analyzes the formation of such two types of heritage sites, scrutinizes the transformation of conservation methodologies, and demonstrates how these two sets of spatial particularities had influenced and shaped the image of the cities. This article thus identifies two ways of ＂spatializing temporalities.＂ Horizontally distributed heritage sites and adjacent areas in Xi'an had been demarcated and labeled individually to guide certain architectural styles. The sense of historical periods was accordingly materialized and located on the map. Rome's superimposed urban history was illustrated in the historical stratigraphy and the collage of relics dated back to various periods.