1 · What a star fort is
Angles instead of walls
A bastioned star fort trades tall straight walls for a jagged ring of angled bastions — every stretch of the perimeter covered by crossfire from its neighbors, and a moat to keep artillery at range. The French engineer Sébastien Le Prestre de Vauban systematized the design in the 1600s to defend France's borders.
From 1802, the Nguyễn court adopted this same trace — via French officers in Nguyễn service and the court's own military engineers — to build citadels the length of Vietnam.
Lighting up the network, one citadel at a time — Huế first.
2 · The network
Nineteen citadels, one system
Từ Huế — the imperial seat, and the brightest point on the map — the Nguyễn court planted the same bastioned trace at provincial capitals from Sơn Tây in the north to Hà Tiên in the south. Nineteen of these star forts survive in the record well enough to map today.
3 · Then faded
Not every wall survived
Two centuries on, the same nineteen points tell a second story. A few citadels still stand whole, inhabited and intact. Most have weathered to fragments, or been quietly built over by the modern city. A handful are erased outright — only their footprint legible from above.
Every fort on this map carries its own record: when it was built, who ordered it, and what fills its walls now.
Explore all 19 forts →