A curious edifice, belonging probably to the later Achaemenian times, stands immediately in front of the four royal tombs at Nakhsh-i-Eustam. This is a square tower, composed of large blocks of marble, cut with great exactness, and joined together without mortar or cement of any kind. The building is thirty-six feet high; and each side of it measures, as near as possible, twenty-four feet. It is ornamented with pilasters at the corners and with six recessed niches, or false windows, in three ranks, one over the other, on three out of its four faces. On the fourth face are two niches only, one over the other; and below them is a doorway with a cornice. The surface of the walls between the pilasters is also ornamented with a number of rectangular depressions, resembling the sunken ends of beams. The doorway, which looks north, towards the tombs, is not at the bottom of the building, but half-way up its side, and must have been reached either by a ladder or by a flight of steps. It leads into a square chamber, twelve feet wide by nearly eighteen high, extending to the top of the building, and roofed in with four large slabs of stone, which reach entirely across from side to side, being rather more than twenty-four feet long, six feet wide, and from eighteen inches to three feet in thickness. [PLATE LIII., Fig. 3.] On the top these slabs are so cut that the roof has every way a slight incline; at their edges they are fashioned between the pilasters, into a dentated cornice, like that which is seen on the tomb. Externally they were clamped together in the same careful way which we find to have been in use both at Persepolis and Parsargadae. The building seems to have been closed originally by two ponderous stone doors. [PLATE LIV., Fig. 1.] [Illustration: PLATE LIV.] Another remarkable construction, which must belong to a very ancient period in the history of the country, is a gateway composed of enormous stones, which forms a portion of the ruins of Istakr. [PLATE LIV., Fig. 2.] It has generally been regarded as one of the old gates of the city; but its position in the gorge between the town wall and the opposite mountain, and the fact that it lies directly across the road from Pasargadae into the plain of Merdasht, seem rather to imply that it was one of those fortified “gates,” which we know to have been maintained by the Persians, at narrow points along their great routes, for the purpose of securing them, and stopping the advance of an enemy. On either side were walls of vast thickness, on the one hand abutting upon the mountain, on the other probably connected with the wall of the town, while between them were three massive pillars, once, no doubt, the supports of a tower, from which the defenders of the gate would engage its assailants at a great advantage.