ALG-454. This double natural arch is located on Ti-Spad area of the vast Tassili National Park, wilaya of Illizi, Algeria. The largest opening has an estimated height of 8.0 meters. This amazing double opening is located in the deepest area of Ti-Spad. In this labyrinth formed by many interwining deep corridors GPS does not track any satellite position, so visitor will need to take a lot of time to explore this area to find this arch.