This massive space station is one of the crowning achievements of any civilization, practically guaranteed to be a center of most spacefaring galactic civilizations. This station possesses a biosphere and can comfortably house millions of people, and it will not require any kind of maintenance as there is a built in A.I. that manages everything in the Citadel that is absolutely loyal to you. It will keep the station viable for millennia without any additional resources, and is easily capable of retrieving any resources it needs. This also includes an entire network of Mass Relays around the galaxy to help move between and a large population on the station already here, that sees you as their ruler and are perfectly loyal to you. This population can be made up of any races shown in the Mass Effect universe. The population cap is 13 million, but you can choose less. This will exist somewhere in the galaxy, and a Mass Relay will be in the solar system of the world of your choosing. If you do not have a method of traveling to it easily, there will be a starship that will arrive in a few days to pick you up and provide transit services for you.