The citadel town of Erbil occupies an elliptical-shaped mound about 30 meters high above the natural ground level of the city below. Its long diameter is about 430 meters and its short diameter is about 340 meters. Its overall area is slightly more than 10 hectares (102,000 square meters). It is surrounded by a steep earthen mound in all directions which made it very difficult for any attacker to scale it. The town is largely occupied by traditional courtyard houses reached through a labyrinth of narrow alleyways. The houses that are built on the perimeter are contiguous and form a solid wall very similar to fortified citadels of medieval times.
The earliest scaled cadastral map of the citadel town goes back to 1920 and shows all urban features including plots and alleyways but not buildings.
However, some vertical and oblique photographs were taken of the citadel during the early decades of the 20th Century help identify many urban features. Another scaled map published by the British Army in 1944 shows the citadel and the rest of the lower city in outline only gives an accurate record of the extent of Erbil's status then.