I am a little surprised by what you say. I've been living in Prague for 9 years (moved here, not Czech) and 8 of them I lived in Prague 5 bordering the Old Town, in 2 buildings build in Art Nouveau style, from around 1900. They were renovated, with modern elevators and looked pretty good both inside and outside.The area was very beautiful. Now I live in a communist tower block in Prague 4 and to be honest it's really not so bad. The apartment is OK, kind of small, especially American standards, but what i really like is the way the area was build. For example, in the middle of the area there is a school, a kindergarten and a nursery. And there are plenty of green spaces. This is definitely communist urban planning, but in this case, at it's best.