+SASSANIAN.+ The Sassanian empire, which during the four centuries from 226 to 641 A.D. had withstood Rome and extended its own sway almost to India, left on Persian soil a number of interesting monuments which powerfully influenced the Mohammedan style of that region. The Sassanian buildings appear to have been principally palaces, and were all vaulted. With their long barrel-vaulted halls, combined with square domical chambers, as in Firouz-Abad and Serbistan, they exhibit reminiscences of antique Assyrian tradition. The ancient Persian use of columns was almost entirely abandoned, but doors and windows were still treated with the banded frames and cavetto-cornices of Persepolis and Susa. The Sassanians employed with these exterior details others derived perhaps from Syrian and Byzantine sources. A sort of engaged buttress-column and blind arches repeated somewhat aimlessly over a whole façade were characteristic features; still more so the huge arches, elliptical or horse-shoe shaped, which formed the entrances to these palaces, as in the Tâk-Kesra at Ctesiphon. Ornamental details of a debased Roman type appear, mingled with more gracefully flowing leaf-patterns resembling early Christian Syrian carving. The last great monument of this style was the palace at Mashita in Moab, begun by the last Chosroes (627), but never finished, an imposing and richly ornamented structure about 500 × 170 feet, occupying the centre of a great court. +PERSIAN-MOSLEM ARCHITECTURE.+ These Sassanian palaces must have strongly influenced Persian architecture after the Arab conquest in 641. For although the architecture of the first six centuries after that date suffered almost absolute extinction at the hands of the Mongols under Genghis Khan, the traces of Sassanian influence are still perceptible in the monuments that rose in the following centuries. The dome and vault, the colossal portal-arches, and the use of brick and tile are evidences of this influence, bearing no resemblance to Byzantine or Arabic types. The Moslem monuments of Persia, so far as their dates can be ascertained, are all subsequent to 1200, unless tradition is correct in assigning to the time of Haroun Ar Rashid (786) certain curious tombs near Bagdad with singular pyramidal roofs. The ruined mosque at Tabriz (1300), and the beautiful domical +Tomb+ at +Sultaniyeh+ (1313) belong to the Mogul period. They show all the essential features of the later architecture of the Sufis (1499-1694), during whose dynastic period were built the still more splendid and more celebrated +Meidan+ or square, the great mosque of Mesjid Shah, the Bazaar and the College or Medress of Hussein Shah, all at Ispahan, and many other important monuments at Ispahan, Bagdad, and Teheran. In these structures four elements especially claim attention; the pointed bulbous dome, the round minaret, the portal-arch rising above the adjacent portions of the building, and