As you approach you notice that two of the large stones don't seem to be connected to the wall. You can assume that there is something of great importance behind them or there would not be a guard standing by.
"I'm sorry visitor, I can not allow you to go any farther. This is the entrance to the great altar. Only the Royal family is allowed beyond this point. Perhaps if I had some proof that they trusted you I'd allow you to go further."
Show the guard the symbol of the royal family: