Chang'an · Xi'an icon

Chang'an · Xi'an

Tang-dynasty Chang'an laid over today's Xi'an at real coordinates. Drag a coin across 1,300 years.

Category
Games & Culture
Platforms
Web
Pricing
Free and open source (MIT licence)
Open Chang'an · Xi'an (changan.pomodiary.com) →

Overview

Chang'an · Xi'an is a free web map that places the Tang-dynasty capital of Chang'an on top of modern Xi'an, at true scale and orientation. Tap anywhere on the map and it tells you which Tang ward you are standing in. It was inspired by a layered map at the Shaanxi History Museum, where Tang Chang'an is drawn over the streets of today's city, and it turns that idea into a page that opens instantly on a phone, with nothing to download.

The control at the bottom is a slider whose handle is a Kaiyuan Tongbao, the bronze coin of the Tang. Dragging it blends the map between three states: today's Xi'an, an overlay of both cities, and Tang Chang'an alone. As you move toward the Tang, modern streets fade back and the ward walls, palaces, markets and waterways of the old capital appear, drawn in a painted-on-silk style with cinnabar, gold and malachite colours and vertical ward names.

The Tang city is not drawn freehand. Its layout of 110 wards follows the Chang'an Zhi by Song Minqiu (vols. 7 to 10), consistent with the Tang Liu Dian, and the whole grid is registered to WGS84 coordinates from three Tang remains that still stand on their original sites: the Mingde Gate ruins, the Hanguang Gate ruins and the Danfeng Gate ruins. After registration, without further adjustment, the Giant Wild Goose Pagoda falls in Jinchang ward, the Small Wild Goose Pagoda in the northwest of Anren ward, and the Tang West Market Museum on the old West Market.

An honest note: this is an illustrative reconstruction. Ward boundaries and streets are approximate, the shapes of pools and canals are stylised, and Daming Palace, which was irregular in reality, is simplified. It is meant to help visitors find their bearings, not to serve as an archaeological reference. The in-app Sources & Notes page lists every source and simplification.

Key features

  • A coin slider through time

    A Kaiyuan Tongbao coin is the slider handle. Drag it, or use the presets for Today's Xi'an, Overlay and Tang Chang'an, to move smoothly between the modern city and the Tang capital.

  • Tap to find your Tang ward

    Tap or click any point and a popup names the Tang ward (fang) that spot belonged to. More than 30 well-known wards come with short stories, such as the Pingkang entertainment quarter or General Guo Ziyi's mansion in Qinren ward. A locate button can show the ward for your current position.

  • Then & Now trail

    A side panel lists sixteen places of Chang'an you can still visit today, including the Giant and Small Wild Goose Pagodas, Qinglong Temple, Daming Palace, Hanguang Gate and the West Market, each with a now and Tang comparison card.

  • Layered detail of the Tang city

    The map shows 110 wards, the East and West Markets, the three palace complexes, the Qujiang and Furong garden area, city canals and ten Tang landmarks that no longer stand. A dashed outline of the Ming city wall shows that today's walled old city covers only the northeast corner of Tang Chang'an.

  • Five languages and full sources

    The interface is available in English, Simplified Chinese, Traditional Chinese, Japanese and Korean. A Sources & Notes page explains the textual sources, the registration anchors and the known simplifications.

How to use Chang'an · Xi'an

  1. Open changan.pomodiary.com on a phone or computer. The language follows your browser, and you can change it from the language switcher.
  2. Read the short welcome card and tap Enter to reach the map.
  3. Drag the coin slider at the bottom from now toward the Tang, or tap the Overlay preset to see both cities at once.
  4. Tap anywhere on the map to see which Tang ward that spot was in; famous wards show a short story.
  5. Open the Then & Now panel to browse the sixteen surviving sites and compare each one's present and Tang-era identity.
  6. Switch to the pure Tang view and look for the dashed Ming wall outline to see how small the present walled city is compared with Chang'an.
  7. Before relying on a detail, check the Sources & Notes page for how the reconstruction was made and where it is approximate.

Who it’s for

  • Visitors to Xi'an who want to know what stood under their feet in the Tang dynasty while they walk the city.
  • Readers of Tang poetry and history who want to place names like Pingkang ward or the West Market on a real map.
  • Teachers and students looking for an easy way to show the scale of Chang'an compared with modern Xi'an.
  • Developers and map enthusiasts interested in an open-source example of registering a historical city plan onto real coordinates.

FAQ

Is it free, and do I need an app?
It is free and runs in the browser on phones and computers, with no app to download. The code is open source under the MIT licence.
How accurate is the Tang city on the map?
The ward layout follows the Chang'an Zhi and Tang Liu Dian, and the grid is positioned from three Tang gate sites still on their original locations. Ward boundaries and streets are approximate, though, and the waterways are stylised, so it should not be used as archaeological evidence.
How big was Tang Chang'an compared with the walled city today?
According to the sources used by the map, the outer city measured about 9.7 km east to west and 8.6 km north to south. The present Ming city wall, shown as a dashed line, encloses only the northeast part of that area.
Which languages does it support?
English, Simplified Chinese, Traditional Chinese, Japanese and Korean. If your browser language is not one of these, it defaults to English.
Where does the base map come from?
The modern base map uses OpenFreeMap vector tiles built on OpenStreetMap data, which use the same WGS84 coordinates as the reconstruction, so there is no coordinate offset between the two layers.

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