diff --git a/README.md b/README.md
index ec6a9c8..cb267db 100644
--- a/README.md
+++ b/README.md
@@ -107,6 +107,12 @@ interface CalendarEngine {
 
 Register with `registerCalendar('my-id', myEngine)`. Then pass `{ calendar: 'my-id' }` to any conversion function.
 
+## Architecture
+
+The UAQ engine performs a binary search over the 184-entry table — O(log 183) per conversion. The FCNA engine computes new moon times using the Meeus Ch. 49 algorithm (3 to 5 trigonometric evaluations per call). The registry pattern lets any consumer add custom calendar systems at runtime without modifying the core.
+
+For more detail see the [Architecture wiki page](https://github.com/acamarata/hijri-core/wiki/Architecture).
+
 ## Compatibility
 
 - Node.js 20, 22, 24