Bow to the Thrones
In An Tir, it is customary to bow to the thrones (occupied or empty) if you are passing in front of them.
This custom does not exist in all kingdoms.
Tobias writes: "Here in An Tir, we hold the King and Queen in very high regard and bow whenever they are near. We see their thrones as the seat of their authority and we bow to it as we pass within 60 feet (75 if they're ladies' feet) in front of them, even if they are empty. We do this not to show respect to a piece of furniture, but so others may know that we acknowledge and respect the King and Queen of our lands."
For more information see Royal Presence