Period Brak E witnessed the building of the city's walls, and Tell Brak expansion beyond the mound to form a lower town. By the late 5th millennium BC, Tell Brak reached the size of c. 55 hectares. Area "TW" of the tell (Archaeologists divided Tell Brak into areas designated with Alphabetic letters. See the map for Tell Brak's areas) revealed the remains of a monumental building with two meters thick walls and a basalt threshold. In front of the building, a sherd paved street was discovered, leading to the northern entrance of the city.