We have indeed built structures on Mars, but you cannot see them as they are within 4th Density. This is one of our homes at the present time! Mars as a planet is not in 4th Density, but just as we live on the surface of the Earth in 4th Density, in preparation for the Transformation to 4th Density, so we have taken up residence on a planet with a similar gravity field - Mars. Should you visit one of our 4th Density homes, you would find it equivalent to a floating space station. Then why do we not simply take up residence in space? Through methods unknown to you we have approximated the gravitational field of Earth in the center of our circular grid of residences. Call it psychological, if you wish, but knowing we are living on a close brother of the Earth, approximating size and composition and proximity to the Sun, while we wait out the time until we can join our human brethren in Service-to-Other camps, is somehow different than floating out in space.