Green Sector, also known, as the diplomatic sector was restricted to diplomatic and command personnel.
Green Sector contained ambassadorial suites, conference rooms, the Zen Garden and hydroponics.
The "Alien Sector" was the name given to an area of Green Sector specifically adapted to accommodate the different atmospheric needs of 14 different species residing on the station, located between the docking bays and Red Sector. Since most of Babylon 5's residents were natural oxygen breathers, access to and from the Alien Sector was maintained through a series of airlocks, in which standard Breather masks capable of being used by most races were available for use in dispensers. In a somewhat ironic twist, the residents of this area tended to refer to the larger, oxygen-rich part of the station as the "Alien Sector".
Aside from pressurized quarters and public areas, the gravity of specific areas could be manipulated by altering the rotational speed of some of Babylon 5's inner sections. 
This area was originally the meeting place for the representatives of the League of Non-Aligned Worlds and the Babylon 5 Advisory Council. Following the dissolution of the League, the chambers continued to be used for much the same purpose by the members of the Interstellar Alliance and the Advisory Council. Entry is for authorized personnel only, however, Council meetings (with the exception of closed sessions) could be viewed on BabCom Channel 57.
The gardens in Green sector were used to grow hydroponic crops and create oxygen for breathing and while the Garden's primary function is hydroponic crops and oxygen reclamation. Station regulations prohibited use of the Garden for growing personal plants and foods. Laurel Takashima, however, was able to talk a hydroponic gardener into allowing her to grow coffee beans in a few planters.
The Zen Garden was frequented by the ambassadorial staff and some of the crew from time to time. Jeffrey Sinclair arranged to have the space set aside despite the small amount of space available in the station's design. The zen garden features a japanese stone garden. This is a form of art where sand and rocks are organized into various patterns. Delenn once observed that the garden was quite effective in representing the power of one mind to change the universe.
A variety of lecture halls can be rented in both Green and Blue Sector. Some offer seating for no more than 20, while there are two facilities that can hold as many as 250. All the halls come equipped with a full range of audio and visual equipment.