SpaceX recently completed its second 'hop' test for its Starship rocket prototype.
The goal is to use Starship to take astronauts to the Moon, Mars and beyond.
"I want to emphasize, this is a very hard and dangerous and difficult thing.
"Not for the faint of heart. Good chance you'll die. And it's going to be tough, tough going, but it'll be pretty glorious if it works out."
To get to this Mars city goal, Musk seems to have a rough timeline set in place.
SpaceX are working on a Super Heavy rocket booster, which could be ready to test by the next Starship event which is in October.
Musk claimed via Twitter that SpaceX might be giving a progress update report in the same month.
In 2021, Musk has said Starship's first orbital flight would "probably" happen.
Musk said during the ExploreMars.org interview: "The first ones might not work.
"This is uncharted territory. Nobody's ever made a full reusable orbital rocket. Just having that at all is pretty significant."
After this, Musk wants to send Japanese billionaire Yusaku Maezawa and six to eight artists around the Moon in 2022.
Musk is aiming for Mars cargo missions by 2022 and a manned Mars mission by 2024.