I Have Fulfilled My Part Of The Bargain
Atop the tallest skyscraper in a city as future-looking as it was magnificent, two aliens stood side by side. The sky was inky black, the clouds so low they could almost touch them with their fingertips when they raised their hands.
This city was somewhat odd. Its size was that of a small town, but the buildings had very random shapes and volumes. Periodically, after the death of a certain number of individuals, the city would reconfigure itself, the buildings changing in architecture and size.
A room that looked like a small cave just large enough to house a dwarf or a gnome could suddenly turn into a gigantic tree house capable of catering to the most whimsical dryad.
Each of these buildings had its own setting and size at any given time. It could be an anti-matter sphere, a vacuum zone, a star core or even the most ordinary brick and concrete mansion.
The key point was that there were exactly 10,000 buildings. This place was known as the Celestial City.