But little was known of Assyrian art prior to 1843, when the excavations of Botta, the French consul at Mosul, followed soon after by those conducted by Layard, brought to light many ruined buildings, in which bass-reliefs, inscribed stones and metals, and other important relics were found, enabling historians to form a consecutive account of the government, warfare, and arts practised by a people whose cities have lain buried and whose very name has almost been forgotten for over two thousand years. The explorations were made in Nimrod, Koyoundjik, and Khorsabad. The palace of Asshur-bani-pal, erected at Nimrod, in the ninth century B.C., is situated upon a terrace, or platform, approached by a wide staircase, and preceded by two gates decorated with winged bulls. These winged bulls, or lions, were placed as the guardian deities, at the portals of all the great Assyrian palaces, after the manner of the Egyptian sphinxes, not standing isolated like these, however, but built into the masonry, one side or the front and one side only, being carved. The head was human, with long beard and hair, and surmounted by a helmet, the wings large and proportioned to the body. As Sir Henry Layard remarks, it would have been difficult to find more fitting symbols to express at once the wisdom, power, and ubiquity of a supreme being. The chief apartments of the palace are a large assembly hall, 152 feet in length by 30 feet in width, and a number of smaller chambers and banqueting-halls, ranged around an open court. The walls of the great hall were decorated with bass-reliefs, representing triumphal processions, carved upon slabs of gypsum eight feet in height. The palace of Esarhaddon, erected in the seventh century, on the same terrace, contains a large hall, 165 by 62 feet, divided in its length by a wall, surmounted by a gallery of columns. One of the only well-preserved ramps which has been discovered was that leading to this palace. At Koyoundjik, opposite Mosul, the palace of Sennacherib was found at the Southwest corner of a mound a mile and a half in circumference. It contained a vast number of courts and halls, decorated with bass-reliefs and winged bulls, and two colossal statues. The palace of Sargon at Khorsabad, erected in the year 704 B.C., is among the best preserved. Like the others it is placed upon an artificial terrace, enclosed by a wall a mile long on each side. It was defended by a citadel of eight towers with doors flanked by winged bulls. The palace was reached by a long, narrow passage leading to a court and entered through three great gates. The bulls of the central portal were 19 feet high. On each side were two bulls, 13 feet high, with the figure of a giant strangling a lion between them.