One thing that immediately stood out while walking along the two most famous beaches of Rio (and I noticed in Sao Paulo as well, but haven't had a chance to talk about yet), is the presence of fences. Many of the beautiful modernist buildings that were originally supposed to be open to the street are now barricaded behind giant fences with security cameras and guards watching your every move.
I wonder how the walk along the Ipanema beach was 30-40 years ago, but I'm sure it it look very different from this: