diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -2,4 +2,8 @@ FourDjs
 =======
 
 Visualisations of four-dimensional polytopes projected into 3-space, rendered
-with three.js
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+with three.js
+
+![a ball-and-stick visualisation of a 24-cell, a complicated 4D object](docs/screenshot-24cell.png)
+
+[Basic interactive demo](https://etc.mikelynch.org/fourjs/)
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diff --git a/docs/screenshot-24cell.png b/docs/screenshot-24cell.png
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