RIO DE JANEIRO (in full, SAO SEBASTIA0 DO RIO DE JANEIRO, colloquially shortened to Rio), a city and port of Brazil, capital of the republic, and seat of an archbishopric, on the western side of the Bay of Rio de Janeiro, or Guanabara, in lat. 22° 53' 42" S., long. 43° 13' 22" W. (the position of the observa tory). The city is situated in the south-east angle of the Federal District, an independent district or commune with an area of 538 sq.m., which was detached from the province of Rio de Janeiro in 1834. The city stands in great part on an alluvial plain formed by the filling in of the western shore of the bay, which extends inland from the shore-line in a north-westerly direction between a detached group of mountains on the south known as the Serra da Carioca, and the imposing wooded heights of the Serra do Mar on the north. The spurs of the Carioca range project into this plain, in some places close up to the margin of the bay, forming picturesque valleys within the limits of the city. Some of the residential quarters follow these valleys up into the mountains and extend up their slopes and over the lower spurs, which, with the hills covered with buildings rising in the midst of the city, give a picturesque appearance. At the entrance to the bay is the Sugar Loaf (Pao de Assucar), a conical rock rising 1,212 ft. above the water-level and forming the terminal point of a short range be tween the city and the Atlantic coast. The culminating point of that part of the Carioca range which projects into and partly di vides the city is the Corcovado (Hunchback), a sharp rocky peak, 2,329 ft. high overlooking the Botafogo suburb and ap proachable only on the wooded north-west slope. Considerably be yond the limits of the city on its south-west side, but within the municipality, is the huge isolated flat-topped rock known as the Gavea, 2,575 ft. high, which received its name from its resem blance to the square sail used on certain Portuguese craft. The sky-line of this range of mountains, as seen by the approaching traveller some miles outside the entrance to the bay, forms the rough outline of a reclining figure called "the sleeping giant."
The entrance to the bay, between the Sugar Loaf on the west and the Pico on the east, with fortress of Santa Cruz on one side and the fort of Sao Joao on the other, is about a mile wide and free from obstructions. Almost midway in the channel is the little island and fort of Lage, so near the level of the sea that the spray is sometimes carried completely over it. On the west is the semicircular bay of Botafogo, round which are grouped the resi dences of one of the richest suburbs; on the east, the almost land locked bay of Jurujuba. (See NICTHEROY.) The bay extends north ward nearly 162 nautical miles, with a maximum breadth of 11 m. The irregular shore-line has been modified by the construction of sea-walls and the filling in of shallow bays. Close to the shore are the islands of Villegaignon (occupied by a fort), Cobras (occupied by fortifications, naval storehouses, hospital and dry docks), Santa Barbara and Enxadas, the site of the naval school.
The oldest part of the city, which includes the commercial section, lies between Castle and Santo Antonio hills on the south and Sao Bento, Conceicao and Livramento hills on the north, and extends inland to the Praca da Republica, though the defensive works in colonial times followed a line much nearer the bay. This section during the 19th century extended southward along the bay shore in a string of suburbs known as the Cattete and Botafogo, with that of Larangeiras behind the Cattete in a pretty valley of the same name, and thence on or near the Atlantic coast as Largo dos Leoes, Copacabana and Gavea, the last including the botanical garden. The greatest development has been northward and west ward, where are to be found the suburbs of Cidade Nova, Sao Christovao, Engenho Novo, Praia Formoso, Pedregulho, Villa Isabel, Tijuca, and a number of smaller places extending far out on the line of the Central railway. The extreme length of the city along lines of communication is little less than 20 m. The popula tion (estimate of 1933) was about 1,500,00o.