Of the old time entombed. (40)
This is another strong death image. We've already been told to "mourn" for the king, and now we're told that the past ("old time") has been entombed—laid away like a dead body in the ground. The happiness we felt and saw in the opening stanza is dead and gone, just a distant memory.
And laugh—but smile no more. (48)
The spirits of the palace still make the sounds that are supposed to go along with happiness. They still laugh, but all the joy is gone, and the simple, genuine smile of happiness is long gone. The fact that the poem ends with this image helps us to see how important the loss of happiness is in "The Haunted Palace."