From the Museums of Metz, here's a bird's-eye view of Metz and its fortifications in the 17th Century. Just above the cathedral, on the open field at the left of the little island in the Moselle, is where the Temple Neuf now stands. The city walls have mostly now disappeared, except for the ramparts at the junction of the Moselle and Seille, at the right side of the city in this picture. The elaborate fortification on the left was the Porte Serpenoise, now shrunk to an arch. Overall, Metz must have been a formidable defensive position.