In 2009, astronaut Buzz Aldrin caused a stir when he suggested we should attempt to visit the monolith on Phobos, the largest of Mars's two moons, before heading back to our own. "We should go ...

In most cases, the stelae mark elite and royal burial tombs. The largest stelae appear to decorate the graves of the Aksumite kings. The monoliths are spread over multiple terrains, including fields ...