E.U.N. Maximum-Security Prison

Hello everyone,
Earth has become a peaceful planet under the E.U.N. (Earth United Nations) until the alien invasion. The war between the E.U.N. (Earth United Nations) and the aliens has been going on for decades and brought humanity on the brink of extinction. While wars ravage the Earth, E.U.N has sent people to explore and settle colonies on other planets.
I started with designing a city that would become the capital for the E.U.N. on the new planets, but felt like it was unfinished or did not tell a story yet. I then decided to change it to a maximum-security prison that would house all the most dangerous aliens.
Thanks for viewing. Stay tuned for more concepts.