Known as the Serra da Carioca, and the imposing wooded heights of the Serra do Mar on the N.
The spurs of the Carioca range project into this plain, in some places, closely up to the margin of the bay, forming picturesque valleys within the limits of the city.
The culminating point of that part of the Carioca range which projects into and partly divides the city is the Corcovado (Hunchback), a sharp rocky peak 2329 ft.
The water supply is derived from three sources: the small streams flowing down the mountain sides which serve small localities; the old Carioca aqueduct, dating from colonial times, which collects a considerable supply from the small streams of the Serra da Carioca and brings it into the city through a covered conduit which once crossed the gap between Santa Thereza and Santo Antonio hills on two ranges of stone arches (now used as a viaduct by the Santa Thereza Tramway Company); and the modern Rio do Ouro waterworks, which brings in an abundant supply from the Serra do Tinqua, N.W.
The new Praca do Commercia (Merchants' Exchange) and Post Office on Rua 1 ° de Marco, and the national printing office near the Largo da Carioca, are notable examples.