כָּל־אִישׁ וְאִשָּׁה אֲשֶׁר יָבוֹא־אֶל־הַמֶּלֶךְ אֶל־הֶחָצֵר הַפְּנִימִית אֲשֶׁר לֹא־יִקָּרֵא אַחַת דָּתוֹ לְהָמִית

Entering the inner courtyard without permission was punishable by death.

Below is a picture of the floor of the inner courtyard in the ruins of the palace of Shushan.