Largest city in the Southern Hemisphere
Iguazu Falls :
Triple Frontier : The Triple Frontier is a tri-border area along the junction of Paraguay, Argentina, and Brazil, where the Iguazú and Paraná rivers converge.
In this picture on your left Argentina. On your right Brazil and Straight ahead where it seems the river ends (actually the confluence point of Iguazu River and Paraná river) is Paraguay.
Oscar Niemeyer architecture
The mouth of the Rio Negro at the "Meeting of Waters": the dark Rio Negro meeting the silty Amazon River.