Archaeological Institute and Department of Culture and Information of Hanoi have made archaeological excavations inside Doan Mon vestige. As a result, at the depth of an yard covered by the brick, stone jetty of the Le Dynasty; at the depth of the road, covered by the lemon flower-colour brick, of the Tran Dynasty, below it is old road foundation of the Ly Dynasty have been found. With this information, we have investigated in order to get information for determining these old road foundations around Doan Mon vestige in the direction of old road foundations found inside.
