Mirror world, kinda :)

Titan is the only world besides Earth with rivers, rain and seas on its surface, though the liquid is methane and ethane and the bedrock is water ice. Representative image. Photo: Zelch Csaba / Pexels.

If man wants to colonize the solar system, the place to go is Titan. Why? It's atmosphere is 1.5 times denser than earth's, the hydrocarbons are endless in terms of easy access to energy and gravity's 14% of Earth's. Compare this to Mars, virtually no atmosphere, which means radiation from the sun becomes dangerous. The pressure suits must not only protect the explorer from radiation but also must be pressurized, complete with air supply and heat, due to the lack of a viable and safe atmosphere. With Titan, no need to pressurize, just heat and air supply are the requirements. In terms of costs, a no brainer. Self sustaining applies and, you don't have to be underground in order to survive on Titan while on Mars, you do. Downside. It's far away.

Titan's orbit (highlighted in red) among the other large inner moons of Saturn.
The moons outside its orbit are (from the outside to the inside) Iapetus and Hyperion;
those inside are Rhea, Dione, Tethys, Enceladus, and Mimas.

Saturn’s largest moon, Titan, is the only place besides Earth known to have standing liquid on its surface, and with it rivers, rain, clouds, lakes and seas fed by a weather cycle that runs much like our own. The catch is in what the ingredients are. The rain and the rivers are liquid methane and ethane, and the ground they cut through is water ice, frozen so hard at Titan’s temperatures that it behaves like rock.

It is the closest thing in the solar system to a working copy of Earth’s landscape, built from a completely different set of materials.

Vertical diagram of Titan's atmosphere

Most of what we know came from the Cassini-Huygens mission, a joint effort of NASA, the European Space Agency and the Italian Space Agency. Titan’s thick, hazy atmosphere hides its surface from ordinary cameras, so Cassini mapped the ground with radar from orbit over more than a decade.

The closest look came on 14 January 2005, when the European Huygens probe parachuted down through the haze and landed, the first and so far only landing in the outer solar system. On the way down it photographed branching networks that looked unmistakably like river valleys draining into a darker, flatter plain. It came to rest on a surface strewn with rounded cobbles of water ice, smoothed as if they had been tumbled along by a flowing liquid. The landing site had the look of a dry streambed.

Earth image derived from DSCOVR/EPIC. Titan image derived from Cassini spacecraft narrow-angle camera (NAC). The relative sizes are calibrated using the known distances to each target at the time of image acquisition and the angular resolution of the respective instruments. Titan’s apparent size includes its extended atmospheric haze.

Structure of Titan's icy crust

Cassini, gone but not forgotten