It’s difficult to choose, but here are some of the notable sights in Buenos Aires.
Puerto Madero (photos) began operating as the main commercial port for Buenos Aires in 1897. It is located very near to Plaza de Mayo and the Pink House. It gets its name from its designer, Eduardo Madero. Only 30 years later it was replaced by Puerto Nuevo. For the next 50 years Puerto Madero was left to deteriorate.
The Rio de la Plata flows south forming a border between Uruguay and Argentina and then opens into a large bay. Buenos Aires and Montevideo (photos) sit on opposite sides of this bay about 130 miles apart, Montevideo being to the east and a little south of Buenos Aires. The easiest way to travel from one to the other is over water since the land route is quite long.