At a short distance from the palace was the "Acra," or citadel, an
artificial structure, if we may believe Polybius, and a place of very
remarkable strength. Here probably was the treasury, from which Darius
Codomanus carried off 7000 talents of silver, when he fled towards
Bactria for fear of Alexander. And here, too, may have been the Record
Office, in which were deposited the royal decrees and other public
documents under the earlier Persian kings. Some travellers are of
opinion that a portion of the ancient structure still exists; and there
is certainly a ruin on the outskirts of the modern town towards the
south, which is known to the natives as "the inner fortress," and which
may not improbably occupy some portion of the site whereon the original
citadel stood. But the remains of building which now exist are certainly
not of an earlier date than the era of Parthian supremacy, and they can
therefore throw no light on the character of the old Median stronghold.
It may be thought perhaps that the description which Herodotus gives
of the building called by him "the palace of Deioces" should be here
applied, and that by its means we might obtain an exact notion of the
original structure. But the account of this author is wholly at variance
with the natural features of the neighborhood, where there is no such
conical hill as he describes, but only a plain surrounded by mountains.
It seems, therefore, to be certain that either his description is a pure
myth, or that it applies to another city, the Ecbatana of the northern
province. It is doubtful whether the Median capital was at any time
surrounded with walls. Polybius expressly declares that it was an
unwalled place in his day and there is some reason to suspect that it
had always been in this condition. The Medes and Persians appear to have
been in general content to establish in each town a fortified citadel or
stronghold, round which the houses were clustered, without superadding
the further defence of a town wall. Ecbatana accordingly seems never to