Dome

Sculpture representing the River Danube, rear view, located at the southwest corner (design is by Bernini but executed by pupil Antonio Raggi); The actual carving of the sculpture was done by assistants to Bernini. Its travertine base, populated with four giant marble personifications of the rivers Danube, Nile, Ganges and Plate [the four great rivers in the four continents recognized by the Renaissance geographers: the Nile in Africa, Ganges in Asia, Danube in Europe, and Río de la Plata in America. Each has animals and plants that further carry forth the identification.]... supports an ancient granite obelisk moved from the Circus of Maxentius. Bernini daringly pierced the base on all sides, thus opening a view through and making the massive obelisk appear to hover weightlessly above the void. Source: Grove Art Online; http://www.groveart.com/ (accessed 11/15/2007)