The walls were tiled and decorated with pictures of lions, bulls, and flowers. Darius ordered his name and the details of his empire to be written in gold and silver on plates, which were placed in covered stone boxes in the foundations under the Four Corners of the palace. Two Persepolitan style symmetrical stairways were built on the northern and eastern sides of Apadana to compensate for a difference in level. Two other stairways stood in the middle of the building. The external front views of the palace were embossed with carvings of the Immortals, the Kings' elite guards. The northern stairway was completed during the reign of Darius I, but the other stairway was completed much later.