Mercado de Abasto
The work of Slovenian architect Viktor Sulčič, who also designed La Bombonera [link to Best places to watch sports in BA], this swooping, soaring brute of a building is my favorite in Buenos Aires. Built in 1934 as a wholesale fruit and vegetable market, it was transformed into a shopping mall in 1998. The great arches of reinforced concrete are imposing by day, but morph into something more graceful when lit up at night.