http://www.paranormalnews.com/news.aspx?nCategoryId=10
Mars is probably as old as the earth with just as many secrets & mysteries.
http://paranormal.about.com/library/weekly/aa020904a.htm
http://marsandufosmysteries.blogspot.com
http://www.dailymail.co.uk/sciencetech/article-2195131/More-evidence-life-Mars-Nasas-Curiosity-spots-alien-picking-Dr-Martens-boot.html
Mars is close enough to eventually build bases & cities on & under the surface of the planet. Perhaps several secret space programs have already been there many times & built some new habitats, in addition to finding some ancient ones.
http://desert-shapes.blogspot.ca/2013/04/mars-desert-research-station-mdrs.html