[PLATE LIII., Fig.

2.] [Illustration: PLATE LIII.] 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.