Uranus is composed primarily of volatile materials heavier than hydrogen and helium, such as methane, water, and ammonia. It has no solid surface, instead having a steadily thickening atmosphere composed of hydrogen, helium and methane which gives way to a thick, liquid, ice-rich mantle as depth increases, ending eventually in a solid rocky core.
Uranus is an unusual world in that its axis of rotation is almost parallel to the Sol System's natural orbital plane. Due to this anomaly, the planetary poles receive more light from the sun than the equator. The cause of this unusual tilt is thought to be from an impact between Uranus and another protoplanet early in the Solar system's history. The Uranian magnetic field is dramatically offset from the planet's center of mass and not aligned with its rotational axis.
Uranus formed as most of the gas giants in the Sol System did. Gasses near one of the larger rocky bodies began to coalesce and form a large gas giant planet. At some point during its history, Uranus was impacted by another body in such a way that the planet was completely tilted off of it's orbital axis. Thus, all moons which orbit Uranus now orbit within its current rotational axis.
There is a possibility that it was discovered early in human history, being misidentified as a star possibly by Hipparchus of Nicaea in 178 BCE.
The earliest conformed sighting of Uranus took place in 1690, when English astronomer John Flamsteed observed it at least six times, cataloging it as a star he named 34 Tauri. The French astronomer Pierre Charles Le Monnier observed Uranus at least twelve times between 1750 and 1769.
However, it wasn't until March 13, 1781 where an official discovery was made by by Sir William Herschel. He too, however, misidentified it as a comet and for two years he continued to identify it as such despite his colleagues describing it as a primary planet. However in 1783 he eventually admitted that it was a planet.
In 1986, NASA's Voyager 2 interplanetary probe flew by Uranus. This flyby remained the only investigation of Uranus carried out from a short distance until the Great Solar System Tour where humans actually visited the planet.
With the discovery of Warp Drive technology, more and more researchers moved to Uranus' moons in order to study the unique planet from up close.
With the advances in dirigible cities, it was inevitable that Uranus would eventually have one constructed. Kronos 1, named after the mythical son of Uranus from myth, was initially a research station set in orbit to study the atmosphere in greater detail. From there, many other different floating cities began to be built.
Today, much like the rest of the gas giants, massive floating continents and cities exist within the clouds.