Take the first turn on your right at the Gates of Orgrimmar and continue straight until you notice stairs leading down to the Portal Room.
The interior houses 7 portals, various NPCs, and what appears to be a dragon husk of sorts.
Starting from the right, we have portals to:
Dalaran (Crystalsong Forest).
Portal to Honeydew Village (Pandaria)
Portal to Zuldazar (Zandalar)
Portal to Azsuna (Broken Isles)
Portal to Warspear (Ashran)
Portal to Shattrath (Outland)
Portal to Silvermoon
All portals from the Drag were removed with the exception of the Broken Shore portal to Dalaran.
The Alliance Portal Room is located in the Mage Tower and it’s bigger than its Horde counterpart.
Once you enter the portal, you’ll notice a path leading to a room with Mage and Portal trainers.
There, you can turn left for portals to Ashran, Boralus, and Azsuna, or right, for the remaining four portals.
On the left, there are portals to Dalaran (Crystalsong Forest) and Exodar.
On the right, we have a portal to Honeydew Village in Pandaria, and Shattrath.