The Plaza de Mayo is probably the most significant square of Buenos Aires. An obelisk stands in the middle of the centrally located plaza.
The Plaza de Mayo is surrounded by the pinkish Casa Rosada (the Argentine equivalent to the White House), the main cathedral (Catedral Metropolitana) with the bank-like neoclassical facade, and other important banks and institutions like the Cabildo. The wide Avenida de Mayo connects the plaza to the grandiose National Congress (Palacio del Congreso) to the west.
The spacious Plaza de Mayo is a frequent location for political protests. I witnessed a slew of protesters (September 2001) who had paraded down the Avenida de Mayo and then congregated in the Plaza de Mayo. It was rather festive, with drummers drumming and chanters chanting, but not violent. Perhaps this was a sign of things to come later in the year, as the fragile economy in Argentina collapsed.