A Sector is a technologically advanced floating Dome and is immense in size and scale. They house vast landscapes with their own unique style and backstory.
There are many large floating sectors in each of the Themed Zone and they all have a unique geographical layout.
You enter the Sector by approaching via a flying vehicle (Private or Public) and flying into one of the 4 Hanger Bays as can be seen in this old UE4 preview footage ..
The Hanger Bays take you to the huge Central Terminal where you will be greeted by NPCs, shops and all kinds of interactive objects.
From here, you will enter one of the COPI Subway trams that will take you to one of the Surface Stations. Finally, you will enter the Surface Tube and emerge in your chosen Sector District - quite the trip!
Central Terminal - Public Transport can be seen on the left
Unfinished preview of the Central Terminal Hub