This is the backside of the Teatro Colon, supposedly one of the best opera houses in the world. I've heard 3rd best, after two in Europe, but that could be proud Argentine banter. It is pretty impressive, though. You can see a couple of shots of the inside starting <a href="http://www.flickr.com/photos/birdseyeview/284205953/in/set-72157594353026204/">here</a>.
Unfortunately, they've closed it down for the next year and a bit to do renovations. They've assured everyone that it will be open by May 2008 - that is the centenary of the building, after all - but many are distrustful. Businesses have closed 'for rrenovations' before and never opened again.