'Siwemuergen' means seven 'Muergen'.
A 'Muergen', in French 'arpent', in German 'Morgen', was an old measure of land. The German Morgen was the area a horse- or ox-drawn plough could till in one morning, and its size varied from region to region. The street here is officially the rue des Sept-Arpents. The spot lies on the border between Eich and Rollingergrund.