The Aloba Mountains of the Ennedi massiv are located in the northeastern part of Chad. In this mountains you can find one of the biggest (see the person on the left side in front of the shadow) but sparely visited Arches in the world, Aloba Arch.
It's a long and dusty drive on a piste to the Arch, but well worth it!
UTM Coordinates: 34 Q 632118 1851327
It's dimensions: Span: 77.0 m; Height: 120.0 m.