Viewing platform Buenos Aires

[Londonscraper]

Please excuse me for writing in English but I'm going to be spending my honeymoon in Buenos Aires and am very keen to view the beautiful city from high up. I love architecture so what better way to do it than to find a viewing platform in a skyscraper! Does anyone know if there's one open to the public? Much appreciated if anyone can let me know. My fiance/wife will be over the moon.