A view of the Noctis Labyrinthus region of Mars, perched high on the Tharsis rise in the upper reaches of the Valles Marineris canyon system.Reuters

In a keynote speech titled "Making Humans a Multiplanetary Species" at the 67th International Astronautical Congress (in Guadalajara, Mexico), SpaceX founder and CEO Elon Musk said a city will be built in Mars in the future. Although he didn't mention a time frame as such, he did share significant pointers from the plans he has for the times to come.

 Musk revealed that there would be airline-like flights that would shuttle between the Red Planet and the Earth, with each course taking six months or more to complete. He projected that for his ideas to take shape, he would at least need a $10 billion investment.

"What I really want to try to achieve here is to make Mars seem possible – like it's something we can achieve in our lifetimes," he further added. In his speech, Musk feared that there's an inevitable extinction of human life fast approaching and there are two ways to deal with — vanish or become a "spacefaring civilization, and a multi-planetary species."