Pyramids, monumental structures of stone or brick over the sepulchral chambers of Egyptian kings, built in the well-known pyramidal shape. The most famous are those of Gizeh, on the other side of the Nile facing old Cairo and near the ancient Memphis. The largest, that of Chufu or Cheops, second king of the 4th dynasty (3750 b.c.?), was originally 481 feet high on a square base of 774 feet - higher than St Paul's on an area as large as Lincoln's Inn Fields - but many of its exterior blocks have been removed for buildings in Cairo. The second, that of Chephren, the successor of Cheops, was 450 feet high on a base of 700 feet square. The third is much smaller, and there are six others smaller still at Gizeh; eleven at Sakkara, a few miles S.; others at Abou Roash, Abusir, at Dahshur, at Meydum, in the Fayyum, and in Nubia- Pyr'enees, the mountain-chain that divides France from Spain, stretches from the Mediterranean to the south-east corner of the Bay of Biscay, a distance of 270 miles, its breadth varying between 15 and 70 miles. They form a regular and continuous chain, divisible into the Western, Central, and Eastern Pyrenees. The Central Pyrenees, extending from the Port de Canfranc to the Col de la Perche, contain the highest peaks and the most imposing mountain-masses, as Pic de Nethou (in Maladetta), 11,170 feet; Mont Perdu, 10,998; Vignemale, 10,794; Marbore, 10,673; and Pic du Midi, 9466. On both north and south the mountains sink down to the plains in a series of terraces, with precipitous faces, the slope on the Spanish side being steeper than on the French side. The valleys or ravines cutting into the mountain-mass on both sides terminate in caldron-shaped basins, called cirques or oules (= pots), the sides of which are precipitous and seamed with waterfalls; the most celebrated is the Cirque of Gavarnie, at the head of Gave de Pau, with a waterfall 1380 feet high. The streams on the Spanish side are mostly feeders of the Ebro, whilst the French streams feed the Adour, the Garonne, and some little Mediterranean rivers. The lower Pyrenean valleys through which these streams flow are in many cases covered with grass or forest, or even vineyards and olive-groves. Snow lies on the highest pinnacles, the snow-line being 9200 feet on the south side and at 8300 on the north. A narrow belt of glaciers runs from east to west just below the Central peaks, but almost wholly on the French side. Minerals are not generally abundant, though iron is worked in Basses-Pyrenees and Pyrenees-Orientales; coal exists on the Spanish side and lignite on the French. There are numerous mineral springs (several being hot), those of Eaux-Bonnes, Cauterets, Eaux-Chaudes, Bagneres de Bigorre and de Luchon, and Bareges being the best known. See Count Henry Russell, Pau, Biarritz, and the Pyrenees (new ed. 1891).