Cities in the Skies of Venus
When you hear of colonisation the natural targets of the Moon and Mars are usually mentioned. The surface temperature of Venus is 450 degrees and the atmosphere is mostly Carbon Dioxide which is clearly unworkable. But as the NASA scientist Geoffrey A. Landis said, “However, viewed in a different way, the problem with Venus is merely that the ground level is too far below the one atmosphere level. At cloud-top level, Venus is the paradise planet.” About 30 miles up the climate is practically Medetareanian and there is a fortunate coincidence which makes this fact of particular use. If you took a balloon and filled it with the normal air mixture of Earth, say 71% Nitrogen and 29% Oxygen, then it would float at that level.
If we were to scale this up to the size of a city, you could have a huge dome floating in the sky with the appearance of a snowglobe. Inside the dome the inhabitants wouldn't have to wear protective clothing and the temperatures would vary between 0 and 50 degrees. The gravity at this level is about 0.90g, which is far better than the 0.38g of Mars. This is important because humans tend to lose muscle and bone density in prolonged low gravity and we don't yet know whether Mars’s gravity is high enough to prevent this. If your worry is about the dome ripping and then plummeting to the ground then you are in luck. Since the pressure on both the inside and outside of the canopy would be the same then the two gases would just slowly infuse into each other rather than explosively bursting out, which would provide plenty of time to fix repairs.
The days on Venus last 243 Earth days, but the winds are fairly fast at about 210 MPH. So if you left the cities untethered you could have them float around the planet and have a day-night cycle every 4 Earth days which is better than Mars. I also prefer the idea of untethered cities to create the image of Mortal Engines style cities consuming each other. Dreams of sky piracy seem almost more real on Venus.