First of all, a Roman model was well chosen for so vast a building. The Greeks built no large roofed structures. Their great assemblages were held in open-air theaters and stadia. The Greek masterpiece, the incomparable Parthenon at Athens, was considerably smaller than Oregon's timbered imitation at the Exposition. On the other hand, the solid Roman style lends itself to bulk. The models followed in the Machinery Palace were the Roman Baths, particularly the Baths of Caracalla. They have been used once before as a model in this country, in the building of the Pennsylvania Railway station in New York. There, too, travertine was first successfully imitated by Paul Deniville. Looking at the Palace of Machinery, indeed, it is not difficult to imagine it as the noble metropolitan terminal of a great railway system. It would hold many long passenger trains, and an army of travelers. The distinctive feature of the perspective is the triple gable at the ends of the palace and over the great main entrance. By thus breaking up the long roof lines, as well as by lowering the flanks of the building to flat-roofed wings, a barn like effect was avoided. In the triple gables, also, the three central aisles which distinguish the interior show in the outer structure. Under the gables the huge clerestory windows above the entrances relieve the great expanse of the end walls. Similar windows open up the walls above the flat-topped wings. In the main entrance, the gables are deepened to form a huge triple vestibule where the row of columns is repeated. The long side walls are relieved by pairs of decorated columns flanking the minor entrances. Thus, by entirely simple devices, the long lines and vast expanses of wall are deprived of monotony. The architect has given majesty to the palace, not merely a majesty of hugeness, but of just proportions and dignified simplicity. In the general architectural scheme of the Exposition it forms one end of the main group of palaces, at the other end of which is set the Palace of Fine Arts. Machinery Hall, with its severe massiveness and solidity, is a balance to the poetry and spirituality of the Fine Arts. The main entrance is on the west side, looking down the avenue between the Palaces of Mines and Varied Industries. Perhaps it is better, though, to take a first view of the sculptural decoration at the entrance at either the north or the south end, where almost everything is shown that appears in the more complicated main vestibule.