CAIBO 282 CAISSON prise many of the finest remains of Ara- bian architecture, all dating from the time of the ancient sultans of Egypt. Among these, besides mosques, chapels, and Coptic churches, are several of the ancient gates, an aqueduct for convey- ing water from the Nile to the citadel, the works of the citadel, and the palace and well of Joseph. At Old Cairo are the seven towers, still called the "Gran- ary of Joseph," and serving their an- cient purpose. In the island of Rhoda is the celebrated Nilometer. On the S., outside the walls, are the tombs of the Mamelukes, and on the N. E. the obelisk of Heliopolis. There are also a public been founded till about 970; its citadel was built by Saladin in 1176, and it was the capital of the sultans of Egypt till the time of the Turkish conquest in 1517; since that time it has been the residence of the pashas, governors of the province. It was taken by the French in 1798, and held by them for more than three years. Pop. about 800,000. CAIRO, a city port of entry, and county-seat of Alexander county. 111.; at the confluence of the Ohio and Missis- sippi rivers, and on the Illinois Central, the Mobile and Ohio, the St. Louis, Iron CAIRO, EGYPT library containing a splendid collection of illuminated copies of the Koran; a magnetic observatory, and the Moham- medan college of El Ahzar (originally a mosque), the principal university of the Mohammedan world, attended by 8,000 to 10,000 students from all parts of the East. The suburb of Masr-el-Atiqa, or Old Cairo (first called Fostat, "tent- town"), was the site of the original Cairo, founded about 642 by the Sultan Amru, the town on the present site, a little to the N. of Old Cairo, not having Mountain and Southern, the Cleveland, Cincinnati, Chicago and St. Louis and the St. Louis Southwestern railroads; 150 miles S. E. of St. Louis. It is the trade center of southern Illinois, and has freight and passenger steamer com- munications with all river ports, im- portant manufactures, daily and weekly newspapers, national banks, etc. Pop. (1910) 14,548; (1920) 15,203. CAISSON, a military term, denoting a wooden chest to hold ammunition;
