Though it's official name is Celestial City, it was named Supertown by the young Gods known as the Forever People. Supertown is a vast flying structure that constantly glides over the skies of New Genesis. 

 
It was created in ages past when Izaya, the Highfather, gave some of his power to the builder Goddess Atinai, allowing her to raise and shape a piece of New Genesis landscape and shape it into a massive flying city. 
 
Supertown is the only technologically advanced structure on the otherwise unspoiled paradise planet of New Genesis, and is designed in such a way as to in no way interfere with the planet's ecosystem. all the Gods have abodes in the city. And it is in the towers of this city that the Chamber of the Source is located, where the Highfather communes with the Eternal Source by watching the flaming messages written on the Wall of Prophecy.
The entire city is riddled with statues, paintings and other beautiful works of art which echo the Gods' celebration of life and happiness. In fact the city itself is so beautiful that visitors often stare in awe of the majestic complex, rightfully believing they have come to heaven.
 

The city possesses impressive mobility, and is capable of interstellar travel, demonstrated when Darkseid's use of the Micro Mark cause the destruction of New Genesis. The Supertown was simply jettisoned of the planet awaiting its doom and relocated to another planet as New Genesis was rebuilt. 
 
The Supertown itself has endured much abuse in its days as well. When Orion slew Darkseid within the Source, the following cosmic storm descended on the Supertown, causing the City to crash into New Genesis, destroying it utterly. The Gods scattered about the surface of New Genesis to their own devices, until Takion summoned the spirit of the now deceased Highfather, who recreated the Supertown and gave new life to his people. 
 

The city, along with the entire planet and it's citizens, was again destroyed when Darkseid obtained the Anti-Life Equation. The now homeless Gods went into hiding on Earth, and Darkseid followed them. 
With the defeat of Darkseid, the Gods were reborn and made their way to Earth-51 to make their home there. It is unknown if they will recreate the Celestial City to once again serve as their home.