How to reach Halls of Honor
You can find the Halls of Honor zone line mixed in with 5 other zones inside the cave in central Plane of Tranquility. At the back end of the cave you'll find 5 different sets of stones with Halls of Honor being the northwestern most one of them.
Aside from just clicking the stone in order to enter this zone you'll need to be at least level 62 or have completed the neccessary PoP flagging requirements. If you're still having trouble identifying which stone you need to click on for access to HoH take a look at my map below.